all my indoor plants have topped out a tad over 3 feet, however i'm a indica guy so i'm growing stubby strains, your plants wil most likely triple in size by the end of flower, also you should give them atleast 4 weeks of veg before flowering to let them reach sexual maturity, anything more than that is just going to give you more growth for more flower sites on your plant, but the bigger the plant the longer its going to take to finish flower