so ur in 7 weeks of flowering and its a sativa strain im goin to say that theyll be ready an prime to harvest 10-12 weeks of flowering. and i mean it also depends on what ur growing in ya know. just from the info provided
Just keep checking the trichomes with a microscope.They will turn from clear to cloudy to amber.It's suggested that for an up buzz, you harvest when they're mostly cloudy. If you want a more "Stoned" high, harvest when they're mostly amber.https://www.rollitup.org/view.php?pg=faq&cmd=article&id=157
But you still have at least three weeks left.
yup all in all I think the longest flowering period is around 12 weeks so anytime before then and after 8 weeks your good but to tell for certain even if you know the extact flowering period check your trichs with a micro!!!