Suggest buying a cheap magnifier. Look at trichomes..the white pistils will be almost gone when it's close.
Trichomes are the perfect way to tell if it's ready to your liking, consistently.
I'd say 2 weeks at least if your not planning to use a magnifier.
You won't be disappointed to wait 2 weeks..that being said, with magnifier, if in 2 weeks your trichs are still 50% clear and 50% cloudy you'll know waiting for a other week or maybe only 3 days, would get you some top shelf bud. It's ready when it's ready.
When your trichomes are mostlty cloudy with only a few few amber colored will get you the highest cannabinoids.
Wait a little longer until 10-20% amber and you may find the high a little more relaxed.
Wait until 30-50% amber and couch locked sleepy. Whatever your preference for effects.
Harvest all clear trichomes, you'll have weak weed that give most people a headache after the short lived racy high has passed.
Sometime I use the magnifier to harvest the tops only, which are ready only to find that 3 buds sites down needs 2 more weeks to mature. Giving me more top shelf..harvesting in stages is possible.
My preference is 10% amber on indica dominant and 30% amber on a sativa dominant. Took several harvest to find what I like best in each.
Happy growing, have fun.