I would say until the quarantine time is up and they are nice and healthy/free of disease. When they get about 3 inches long from snout to vent is when I would do a big upgrade since when they are younger they can have a harder time hunting. Have you had a fecal done on them yet? If you don't know how to set up a quarantine tank then I can help you with that

0.1.0 Psuedacris regilla