Personally, I would tell you to wait 'till at least your BK is lvl 10, and try to squeeze in as many other upgrades as you can in the meantime. Because sooner or later you're going to end up doing them, and farming resources is much easier (though boring, as you said) as a TH8.
For me, having the DE Storage full when getting to TH9 and buying + upgrading the AQ right away was the best part of the TH upgrade.

