I would waite on adult enclosure construction. It might sound silly, but given it is your first chondro you will learn alot of husbandry techniques as you and your chondro mature that will help you build a much better enclosure for you and your chondro.
Also notice how i say "first chondro", i was just like you awhile back, thinking "well, i only want one chondro". Point being, if you are a chondro person, there is no such thing as one. And its near impossibal to gauge how many adults you will end up with, so why not waite until your collection grows and pump out a few adult enclosures at one time?