I'd say the window is certainly open!
When you actually cut depends on the effect you'd like, too. As granny said, the trichomes are the easiest way to tell where your plant is at. Clear trichome heads suggest to leave it a little longer (although you can harvest earlier, too, for less potent bud). Milky trichomes say we ready (more energising high, good for pain), and amber trichomes say definitely ready and more couch lock effect (good for anxiety). It depends on personal preference when you harvest... I personally am waiting for around 10% amber before I cut, and already trichs are milky so I could cut any time. I hope that helps!