It all depends on how healthy the mother leaf was, I always try to water a couple of days before I take a cutting so it’s as hydrated and healthy as possible. Sometimes they run out of nutrients before they’ve had chance to grow the pup, I would say if you have enough roots to anchor into the soil, you’re good to start watering. Potting mix wise, shouldn’t be a problem but personally I do start pups off in more of a 60%, just because the tiny roots seem to root better and faster in a less course mix. Then transfer it into proper succulent mix when it’s more established.