I say go for what you really want, as far as which species to keep. Just be sure to do your research first...and bear in mind that they are only cute little babies for a short time...gear your research and consideration toward what it will be like to keep an ADULT snake of that species.

If you're going to switch enclosure types...I'd do that first and make sure you're comfortable with your new routine before adding any new animals to care for.

As for as a specific time frame between acquisitions...I don't think there is one. They're not like dogs or cats that have to interact with each other and require hours a day of training and attention from their owners to stay healthy. It's really just whenever you feel you are ready and have done the research you need to do in order to care for something new.

I will say this: All too often, I see people get caught up in the game of collecting snakes and other critters. They're SO cool...and there are SO many different kinds to choose from...all so beautiful and special in their own right. And even within a single species, there are gorgeous individuals that will always tempt you to want more. There will always be another beautiful animal to want. There will always be another "great deal" that comes your way and is hard to pass up. So, so so often...I see people collecting animals far too fast...and suddenly they find themselves paying hundreds of dollars a month that they can't afford just on rodents to feed them. And the first hint of financial stress (either a vet bill or a car breaking down or whatever)...they suddenly start selling off their collection that they really couldn't afford to keep in the first place. And...despite whatever lesson you think they might have learned....I've seen them start buying up more animals almost right away.

Please, please please avoid this trap. Carefully consider each purchase and look at the long-term consequences of owning each individual animal. There's always more that we want that we can't or shouldn't have.

Sorry to get preachy....that's just been on my heart for awhile now, and you gave me a perfect "out" to release it.