We are skim coating our walls with joint compound. After that, Around how many days or hours, should I wait before applying real paint? Is there any best practice? I hear many drywall say its 3 days standard?
Here is my answer to a similar question: https://diy.stackexchange.com/a/250039/148888
1 rule of thumb? If your guessing, you'll probably be wrong.
Regarding moisture content of any substrate, you can obtain a moisture meter to test it, be it wood, concrete, or plaster.
This is one we use at our paint store. There are less expensive ones and you can find them at any home center.
Technical Service Bulletin on moisture content and different substrates.
I am a General Manager in a local owned, (multiple)paint stores for 21 years.