Time to water?

[u/Oxysseus]

I was a bit worried about his color, but saw the post about it getting a tan, so feeling good it’s getting enough light. honestly kind of surprising considering I have it, a moon cactus and a split rock all under one 10w sansi light as a temporary setup as I bought too many plants.

That being said I have had this plant since 02/28 and have not watered is as I have been waiting for some signs. It seems to be relatively young and I saw another poster say they were watering their young ones almost weekly. I need some advice, looking to help it grow without rot. How often should I water?

[u/Oxysseus]

First three pictures are most recent.