You can keep feeding your Roots Organics products up until the day you wanna start flushing. I aim for letting my girls go 10 weeks, and will start flushing the second the begin week 9, giving them a good 2 weeks. This is because I have very large plants that are well established in the ground with huge root systems. If you're in pots you can probably get away with a week and be more than fine. I just know that with how big my holes are and the PPM I am feeding, they will need a bit longer to fully absorb everything left in the soil and THEN start to feed on all their leaves, which is a lot haha
Flushing is much more vital when you are growing with harsh synthetics n have your plants loaded. While it sounds like you're trying to push your girls as much as you can towards the end, as long as you're not burning, the organics won't be nearly as harsh and should flush out no problem.