They grow fast, but maybe not as fast as you think. Don't expect a "giant" spider within two years. If we're talking about L. parahybana, then they hurry up to get 4-5" and then slow quite a bit down. My 6" girl has been in premolt for the better part of a year now. Stick to a deli cup at that size, and rehouse as needed. For growing slings/juvies, the new enclosures are usually about 5x dls across to allow for at least a couple molts before rehousing again.It's about half an inch.