it depends where you are in terms of location... if your talking outdoor. here in hawaii we have short and long season. short is a couple months while long is about twice the length of time
anywhere from 4 to 7 months depending on how long you veg for. if you want monsters should start em inside till about 2 ft. and put em outside as the days get longer
if your talking indoor its all in your hands when you want her to flower, you control the lighting changes. depends on the setup you have for indoor to determine when to flower