Nice choices! The cobalt blue is a beautiful animal, but as was said before they are extremely fast and aggressive. While their venom is not dangerous, it certainly packs a VERY powerful punch. They are also borrowers so you won't see them often. There's no reason you shouldn't get one even though you're a beginner if you're prepared to respect the animal and take the necessary precautions, but I would say wait at least until you're used to caring for the two that you have coming before jumping into a cobalt. You don't need to do "stepping stone" animals per se, just get used to the behavior first is what I'd suggest.