its possible to be done earlier... but you want to make sure you dont harvest early.... You can use mmultiple methods to determine finished product...
85% or better dark orange hairs, not brown but dark orange.
Checking trics you want mostly all cloudy and depending on the high you want 15-35% amber tric's... note many autos do not give many amber trics, so as long as you have mostly cloudy you should be good.