I caught a couple of male Coleonyx variegatus this weekend. I just have some questions which I couldn't answer with caresheets. I've read that sand is suitable for them, but isn't sand usually considered a bad substrate since impaction can occur? Right now the two are in quarantine and are going to the vet very soon, so should I wait to use sand as a substrate until the quarantine is over? I'm keeping them on paper towels right now.
Here is a picture of their enclosure:
Here are the two geckos:
Here is a picture of their enclosure:

Here are the two geckos:

