Congratulations on your new frog! it would be a good idea to upgrade his terrarium. I would do so as soon as you can, but before he reaches 3". I would go at least 20 gallons, and the taller the better. I'm not sure if you have ever seen them, but I really like the exo terras. They may seem really expensive, but they come with everything you need if you buy the kits. I have a 18x18x24 (which is around 30 gallons) exo terra for my two whites tree frogs.