Max your defences. No exceptions.
Max your lab's elixir upgrades. DE upgrades don't matter too much.
Pour all your DE into your BK. He should easily hit level 8 before you upgrade.
Get all your walls to level 7 (at least).
Then go up.
I've just maxed out my lab's elixir upgrades and have 6 days left until two teslas hit level 6, then my defences are maxed. I've got about 100 level 8 walls, the rest are level 7. I'm going to TH9 once those teslas are done.

