Get a 30-60x jewelers loupe or currency checker.. magnifying glass of some sort. Use color of trichoes to help. google for details. harvest window is a matter of opinion at some point. Do you want couchlock and fall asleep shortly after or to what extent do you want tht end of spectrum etc etc... (ratio of smokey vs amber trichomes, amber is a sign of the degradated thca molecule (=>cba? can google it if you want specifics) and it makes you sleepy)
The stigma haven't retracted yet and at least half are still white, so it looks like it still has some time left. It is torture near the end as it looks like bud, but isn't quite ripe. Using these visual cues with inspection of trichomes will give you best idea of when to harvest... after a couple, you'll feel more comfortable about it. Try a harvest with more amber and with less and decide which you like more over time...
Things will shrink quite a bit when drying - more so if you harvest too early.
so, unless you got a bug problem or a creeeping microbial issue, i'd sit back and let it finish up. nobody can give anything more than a best guess. couple weeks? maybe? I figure once it looks like buds (a bit further along) it's about 1-2weeks more of ripening.