First grow!

Lots of plump left... not yet. Flushing is a tool to fix a problem in the rootzone. It does not influence how flower is constructed. It's bro-science that after the original reasons were debunked, just made up new untested reasons as to why it is necessary before harvest. This is just being stubborn. if your heart is set on it it also depends on the medium. If soil, you can 'flush' longer than in soilless. 10-14 days for soil and 5-7 in soilless will cause a strong fade by the end. You don't want the leaves to run out before it finishes, so err on shorter side, imo. Based on these images, i'd say 7-10 days before you even think about it... and that's assuming the calyxes finish plumping by then.. usually 2-3 weeks from that point to finish ripening.