Which Dragon first + Does it really matter?

[Akimbo]

Hi, I just started today and was wondering about the Pet Dragons. Is the only difference the starting ability and bonus?

For example, if I pick the Blue for the +1 initiative and Mana accelerator. Can I still get access to Mystic Egg etc. later? (Obviously it seems the +1 init. bonus is unique to that pet.)

Sorry if that seems like a stupid question, but I was up early today and my brain's still catching up.