If you have the room for it, you can veg as long as you want to. However, keep in mind that your plant is going to at least double in height when you switch to flower. You have to take into consideration the highest your light can go, and how far away your light needs to be from your canopy. What's left under that and above the top of your pot is how much grow space you have. Once your plant gets halfway to the max height, flower or you'll run out of room faster than you think possible. Hope that helps