How long after Hardwall to skim?

[mrmeanor]

Hello,

I've had to patch up some areas of blown plaster, which I removed and reapplied using Hardwall. How long should I wait until I apply the final skim? It's now the morning after the night before and the plaster has gone off but I can dig my nail into it.

I read that if you don't skim the same day, then you should PVA it first, but the plaster still has an aura of containing moisture rather than being totally dry. The Hardwall is about 8mm.

Many thanks