Since all snakes are different, we need a bit more information. How long is it now? What size tank is it currently in? What is the current age of the snake?
Nobody can maker any kind of reasonable assessment of your snake's needs without a reasonable amount of informatoin...
Here's a little example: my snake is about 5 months old, is 17.5" in length and was just moved from a 10g to a 20g aquarium. In about a year, I will be switching over to a 30" long vivarium to give her enough room to move around. I also plan on picking up a couple '07 hatchlings when the time comes, and they will be housed in 10g aquariums until they are too big for them, at which point they, too, will be moved over to 30" long vivarums.