The three indicators that I use in order of ease are.leaf yellowing,the lower fan leafs start to yellow a couple of weeks before harvest and spread up the plant. By the time leafs in the buds are starting to turn, you're ready.
Pistils, I go with most have turned orange, 50-60% is a bit early for my taste and the added weight in that time is worth it.
Then there's the tric's, I'm letting the ax's go to about 25-30% as they are sativa dom and could do a with a bit of stone.
It's almost a certainty you'll take the 1st one early ,unless you have an iron will. I think everybody does.
So, how are the leafs looking?