Wallpapering on fresh plaster

just look in new build show homes no problem pva walls first dont mist coat

Odd. Get another decorator to quote

When the plaster is dried ,you can prime it and apply the wallpaper IT will only crack if the plaster is too thick skimmed or you have old plaster underneath that hasn't been cleaned off properly

I would get another quote, As-long as the plaster has had time to dry through at room temp and has not cracked within a week there should be no issues. Despite that, any wallpaper that's hung would prevent cracks and effectively 'hold' the plaster together. If the plaster cracks and rips the wallpaper, i would probably give the plasterer a call back!

Why the so called painter said wait 6 months is beyond me. That said if it’s been freshly plastered you need to wait 6 days before painting or papering as the plaster needs time to dry out first

When dealing with new plaster always wait until fully dry, If no cracks have appeared when fully dry the surface is fine to work with. Once dry apply a mist coat to seal the wall, This will also allow more play when hanging the wallpaper.

Once plastered depending on the heating and weather conditions It will be dry within 2 days to mist coat and paint but 1week would help the walls breath and let any moisture dry out .Wall paper can be hung OK if you are hanging a delicate finish wallpaper. it would be then advisable to cross line the walls with a lining paper which provides protection and a solid key to hang the finish paper to. The 6 to 12 month drying out period is the time it takes for a new build property to dry out naturally.Its does not mean you cannot decorate.I hope this helps answer your question.