i put my plants into 1 gallon smartpots from the cups around 10-14 days in. i wouldnt go right to 3 gallons from the cups. you can leave it in if you want, but imo you'd be best off taking and transplanting. Root systems grow really fast, its probably got most of the cup filled by now. Anyway though, i really think you should go to 1 gallons and then move to 3 gallons later on. that what i advise.