Depends on what you're considering "full size". Full size would technically be just short of 4', which is a size that has never been achieved in captivity as far as I know. The usual max size in captivity is about 36", but I can't really tell you exactly how long that takes, since mine hasn't reached that size yet, but generally they grow about 1.5-2" per month until they reach 22-24", then they slow down quite a bit. Mine is about a year and a half old and is about 26" (possibly an inch-1.5" larger).