outdoor plants usually begin showing preflowers by mid-july, or soon after alternating branching is underway. until those preflowers begin producing more on top of each other you can consider the plant in veg...timing is mostly dependant on the strain so an exact or even a close date would only be a guess. but usually, in my area anyway, i can expect flowering to begin around the end of july to mid-august and ending 8-10 weeks later or no later than end of october (frost), for the strains i grow...mostly indica. many strains are done by mid to end of september too and a very few early in august. add weeks to another month for sativa's (in general...the grower must know what s/he is looking for too)