Nice progress so far. I'm happy to see you are prioritizing your DE Drills early on. These are very important as level 6 drills will pay out dividends for you each day that help out a lot with hero and DE based lab upgrades. I'm only a month and a half older than you at TH9 coming from a fully maxed TH8 as well (lab, heroes, defenses, and walls) and can offer you some advice that helped me progress and some things you can consider as you move forward.
What I did was I prioritized all of my elixir upgrades first and got those out of the way as quick as I could. This way any elixir I accumulate over the rest of my time at TH9 goes straight to walls, which helps cut down some time. I suggest going through with your decision to leave a builder off for walls. If you plan to max everything before going to TH10, your heroes will take 42 weeks total to complete, which is 11 months if you keep 1 builder on a hero at a time every week. If you leave 4 builders on defenses, you're looking at 29 weeks of build time or 7 months, which means you would have 13 more weeks of wait time on your heroes or 6.5 weeks if you farmed enough DE to double down on them after your buildings were done. With 3 builders on defenses you're looking at 38 weeks or 10 months of time, which is still under the amount of time for your heroes.
My point here is that there still will be a bottleneck no matter what you do. It's better IMO to save a builder for walls, one on heroes, and 3 on defenses. This way you are basically giving yourself 42 weeks to finish your walls up to level 10 as opposed to only 13 or 6 weeks, which will be really hard to raise the 750,000,000 G/E required to finish out just your lavas. It's idle build time, yes. But you would have that idle build time anyway if decided to max defenses right away and then waited on your heroes. You're basically spreading the idle time over the total time you are at TH9 rather than just the excess time you have once your defenses done if that makes sense. Furthermore, you don't need to wait until each time a builder frees up before you can dump resources into walls.
Furthermore, you are basically giving yourself the ability to utilize your resources effectively without leaving mounds of them available to attackers every time you break your shield. I usually wait until my builders are within 2-3 days of completing an upgrade to start accumulating gold for the next defensive structure(s) upgrade. Any other time in between, I am using any excess gold for my walls, which has been immensely helpful to me defensively. Right now after a little over 2.5 months and have 102 skulls, 120 legos, and 28 lavas.
Let's talk about your DE. You are going to want to collect as much as you can of this each day if you want to keep your lab and a hero going consistently. I'd say you are going to want to be making 180,000-250,000 every 2 weeks to keep your lab busy and a hero upgrade busy consistently. Since I started at TH9, on the DE side, I have already completed Witch level 2, Golems to level 4, and I started my Valk level 3 upgrade a few days ago. My BK is at level 15 and my AQ is at level 11 with 12 set to start as soon as my war ends. And yes, all of my elixir based lab upgrades have been completed besides giants and healers as I never use them.
You may be asking yourself, "Why Valks over say Hogs or Minions?" Though I do tend to agree with the mentality that you should prioritize the things you tend to use the most, I don't see it as being economically effective DE wise. The reason being because early hero upgrades are more inexpensive and also the DE lab upgrades tend to be as well. You can more or less pair an inexpensive, low level hero upgrade with a high costing DE lab upgrade. This way you are knocking out those expensive DE lab upgrades while you are working on the more inexpensive hero upgrades.
To illustrate this, let's say my lab is going to free up soon and I wanted to put my first DE based upgrade and I wanted to start leveling up my BK from level 10 to 15. I know that BK level 11 and 12 costs 45,000 and 50,000 DE, respectively, and will take 2 weeks (I use weeks rather than actual upgrade times as I war once a week and try to plan my hero upgrades around that). Well I can pair that with my Golem level 3 upgrade that costs 70,000 and will also take the 2 weeks. That means that at the time my lab frees up I need to have 115,000 DE (45,000+70,000) available to start those two upgrades with 50,000 DE I need to accumulate in a weeks time.
Fast forward 2 weeks when my Golem level 3 and my BK level 12 upgrades finished and I want to put my BK down to level 13 (55,000 DE) and my Golem level 4 upgrade (80,000 DE) in. I know that after those 2 weeks are up I need to have 135,000 DE saved up to start them and accumulate 60,000 DE by the next week in order to put my BK level 14 upgrade in after 13 finishes up. If I keep doing it that way, by the time I make it to my minion level 5 upgrade that is the cheapest DE upgrade I'll be working on my BK to level 16, which will only cost me 115,000 DE (75,000 + 40,000). That's why I suggest being able to farm 180,000-250,000 every 2 weeks if all of this is making sense because by the time you make it to your last DE upgrade you'll be able to start using all that DE you accumulate from then on for your more expensive hero upgrades.
As the total lab upgrade times take 6 months to complete you want to be chomping down on those DE upgrades early on so you can wrap them all up before your heroes start to get expensive. I recommend leveling your heroes each by 5s (BK 10-15, AQ 10-15, BK 15-20, so on and so forth) to get all of the inexpensive levels done. Again, to illustrate:
|
Days |
Dark Elixir |
| First 2 Weeks |
|
|
| Barbarian King 10-11 |
5.00 |
45,000 |
| Barbarian King 11-12 |
5.50 |
50,000 |
| Golem 2-3 |
12.00 |
70,000 |
| Total |
-1.50 |
165,000 |
|
|
|
| Next 2 Weeks |
|
|
| Barbarian King 12-13 |
6.00 |
55,000 |
| Barbarian King 13-14 |
6.50 |
60,000 |
| Golem 3-4 |
14.00 |
80,000 |
| Total |
-1.50 |
195,000 |
|
|
|
| Next 2 Weeks |
|
|
| Barbarian King 14-15 |
7.00 |
65,000 |
| Archer Queen 10-11 |
5.00 |
55,000 |
| Valkyries 2-3 |
12.00 |
60,000 |
| Total |
0.00 |
180,000 |
|
|
|
| Next 2 Weeks |
|
|
| Archer Queen 11-12 |
5.50 |
60,000 |
| Archer Queen 12-13 |
6.00 |
65,000 |
| Valkyries 3-4 |
14.00 |
70,000 |
| Total |
-2.50 |
195,000 |
|
|
|
| Next 2 Weeks |
|
|
| Archer Queen 13-14 |
6.50 |
70,000 |
| Archer Queen 14-15 |
7.00 |
75,000 |
| Lava Hound 1-2 |
10.00 |
60,000 |
| Total |
3.50 |
205,000 |
|
|
|
| Next 2 Weeks |
|
|
| Barbarian King 15-16 |
7.00 |
70,000 |
| Barbarian King 16-17 |
7.00 |
75,000 |
| Hogs 4-5 |
14.00 |
50,000 |
| Total |
0.00 |
195,000 |
|
|
|
| Next 2 Weeks |
|
|
| Barbarian King 17-18 |
7.00 |
80,000 |
| Barbarian King 18-19 |
7.00 |
85,000 |
| Minions 4-5 |
10.00 |
40,000 |
| Total |
4.00 |
205,000 |
Again it's up to you how you want to progress but this way has been really helpful to me. I've only gemmed approximately 3,000 so far and 90% of that has been put toward boosting my level 6 DE drills and boosting my barracks. The extra DE per week from the drills has been really helpful to me. I normally play 1-3 hours a day and farm strictly in crystal league.
I'll be checking in on you so if you have any questions or need any clarification on anything I can help with that.