Is it time to start flush?

Hello.. Hope all is well.. Ur plants look great.. The yellowing of lower leaves is probably they've used up all the energy they have and is just natural.. Ur top leaves look a bit like over feed(browning on tips).. Personally i still think u have at least 2-3wks left.. Give them a water with no feed..then start to reduce ur feed in ur water.. If u want nicer tasting smoke reduce the food she's having at each interval for a week then start to flush for 7-10days..They will drink slowly last few weeks so dont worry..they look great and if trichomes are milky u know she's not far but u still have white pistol in action so let them glands swell and turn orange.. About 2 3rds of pistols shud of browned off.. Keep up the good work and stay safe.. 👍