She took a LONG time to get big enough to flip to ...

If you are only giving her 1/4 gallon every 24 hours and she's in a 20 gallon pot, you aren't giving her NEAR enough water! Especially at her age! In 20 gallon pots, I'd be giving her that amount when she was week 3 or 4... I grow in 3 gallon pots and I'm giving my ladies 1/2 gallon every day and they're in week 8 (week 5 of flower - they're autos)... When you water, water enough that you're getting at least 10-20% runoff... this helps clear the soil of excess nutes/salts that may be building up which will eventually cause lockout if not taken care of.... Now that they're in flower, they're going to drink a LOT more... you can tell if your ladies need another drink/feed by the weight of the pot... a 20 gallon pot is going to be heavy even when it's dry so if you try to pick it up right after you've watered with some runoff, try to pick her up THEN... you'll see how heavy she is and can better judge her weight when she's dry. As far as defoliation is concerned, I try not to do any until the plant gets into flower... and then only judiciously.. this article has become my "bible" as far as defoliation is concerned - it gives you the when, the why, and the how ... and explains the rationale for all of it... do give it a read! https://www.growweedeasy.com/nebulas-super-simple-3-step-defoliation-tutorial Good luck!