Don’t soak the substrate. Even if it dries fast just add a little bit of humidity. Just use a syringe and put some water on one side of the enclosure. If the substrate doesn’t dry fast in those conditions, mold will grow, potentially killing your tarantula.
@MrGhostMantis looks fine to me, he probably watered and fed it at the same time. A. geniculata appreciates some moist substrate even as adults. I raise almost all my slings on moist substrate, slings dessicate much easier than juvies/adults. Also mold is harmless to tarantulas and it usually only grows on feeders that have been left in too long.
I have heard differently about mold and know people who have lost T’s to it. I know they appreciate a little bit moister substrate but this is crazy wet. I know from experience that you need to be careful with humidity with inverts as when they molt and it is too humid they won’t dry enough and can get hurt.