I've never heard of that, but it's certainly resourceful lol.
If those numbers were realistic, yes. So, if you are speaking theoretically, you can use that to gauge harvest time.
I don't think you are going to run into that problem though. I have not grown hundreds of strains like many people here. But in the few dozen or so that I have run, I have yet to find a single one that finishes in anything less than 70, +/- 2 days. I'm sure there are some that are ready to be cut on day 57, but I haven't seen it.
It's just my educated guess - your week 7 stuff is nowhere near ripe. & if i recall correctly, the rate that thc increases is non-linear. Your week 9 stuff will be far more potent. I think that plant wants 11 weeks. If I end up getting a hold of it, I'm betting the optimal cut down date would be 77 days.
But with the two week window, 9 weeks might be right...who knows...
Fun, Fun, Fun!!