If you haven't shown any real signs of flower, I say you're good to transplant. Better to have the room for the roots later on. Maximize space, maximize yeild. Even so, I think you can move to a bigger pot a week or 2 into preflower. But there will be a bit of lag for the growth to catch up. This being my first round with autos, I can't say for sure. Mine are in 2 gal. Smart pots, for the general rule of every month the plant is alive, give it a gallon of soil. But wish I did 3 gal in case. Next time.