Fireplaces, Heating Stoves, Flues and Chimneys - surface prep redo?

A surface prep was done on my fireplace several months ago with the intent of putting up Cultured Stone. The person who started the job was unable to continue and it now appears will not be able to finish the job therefore I am going to attempt it myself.

My question is, do I have to do anything to the surface prep since it was completed many months ago? The person who did the prep told me that the mortar is not supposed to set before you put the stone up.

The prep consists of wire mesh covered with a sand and mortar mix. The surface is very rough.

Thanks.

I just attended a seminar on cultured stone since I plan to do my fireplace soon. You don't need to redo what's already done, you can continue with what you have there, which is the "scratch coat". You should moisten it with water from a spray bottle before you apply the stones so the scratch coat doesn't suck the moisture too quickly from the mortar you use to set the stones.:)

Thanks for the advice. The seminar is a great idea. I will seek one out in my area and attend before I attempt the job.

Al