it all really depends do you have a indica or sativa, sativas grow alot taller in size it could even triple in size in the flowering stage, indica tend to stay shorter and bushier and will tops double in size. so since you have only around 2 feet left if it is a sativa i would start it within a few more days but if its indica you should let it veg more. and like steezz said you should look in to getting a scrog or you should look into low stress training or LST. this will keep your plant shorter and will increase your yield. i did LST and it worked great havent tried a scrog but have seen people do great things with them. hope this hepled you out and answered your question