cannabis uses the longer dark period to flower usually 10 - 11 hours of darkness can trigger flowering in most strains which is why they naturally flower in the fall for most people in the northern hemisphere you can usually place a 2-3 week old seedling outdoors in the early spring and it will continue to veg even though it may be recieving enough dark hours to trigger flowering in an older plant or clone.
if a plant starts flowering it will have to revert back to veg as the night hours decrease during spring which will slow it down alot to the point where you didnt really gain anything by starting to veg the plant so early indoors to begin with, something to think about so you will check to see how many hours of darkness it will be receiving before you put that 2 month old plant outdoors.