Newly plastered walls should always be allowed to dry thoroughly before being decorated.
As plaster dries it changes colour from a dark pink to pale pink. New plaster will need to be sealed before decoration.
PVA applications are used as a:
There is no need to worry about covering the plaster totally, you just need to give it a ‘mist’ coat to seal the plaster, and you’re not looking for complete coverage. Once you have mist coated your new plaster you can now apply your choice of finish coat and colour.
For wallpapering, the new surface will need to be sized. This is done either with size, or by using a diluted version of the wallpaper adhesive. It is usually best to use an adhesive containing a fungicide. This is particularly important if you plan to hang vinyl paper since it effectively seals the surface preventing it from breathing. See our article about using size