plaster - how long to dry?

[SJPurdy]

It says in BS that plaster walls should be allowed 4 weeks to dry out before tiling. But this is an a section where they are talking about layers of backing plaster followed by finish coat and this time then seems to make sense.
Should it still be 4 weeks if it is only a skim coat over plaster board or a skim coat to make good damage to the old skim where tiles have been removed? Clearly in these cases it dries out in a couple of days normally but do we have to wait for some curing process to take place as well as the physical drying out?
Steve

 

[DHTiling]

Skim to PB IMO is a lot quicker to dry than say to 2 coat..

 

[Bubblecraft]

As Dave says, skimming onto PB will dry far quicker than onto existing painted walls & bonding coats.

There is a 3 step drying process for plaster. The colour it is when it goes on, it will go darker then a very light pink. Plaster on bare PB, in the right environment will dry between 24 to 48 hours.

Original surface:

Step 1 - Applied:

Step 2 - Drying Process:

Step 3 - Dried (Showing a section still drying):

For me, if I were to tile onto a fresh skim coat, I'd leave it to get to the fully dry stage then allow another 24 hrs before tiling