You can flush now if you wanna. Just earlier this week I flushed the day after watering to fix a prob and they didnt even get puffy or droopy from the flush at all

Seeing as your soil pH is prob around 7.8 (if my math is right) its not too acidic, its to alkaline.

IDK for sure but I'd stay away from foliar feeding until you get all the other wrinkles ironed out, no need to throw more wrenches in the gears before you get the first 1, 2, or 3 of em outta there, right?

EDIT: What are your temps at plant height?