I have no idea what the standard procedure is, but our drywaller/painter will do the prime coat after all mudding is done. That seems to make the most sense to me!

And by the way, if anyone is thinking of skipping the prime coat to save any money, don't do it! Painted walls on bare sheetrock does not look good. You can tell a big difference between walls that were primed vs ones that weren't. They are more streaky and uneven in sheen. Even with multiple coats of paint. Ask me how I know! :)

If the painter is using the primer to find defects(it does show them well), that is fine.

However, he needs to apply another coat over the last mud application.

Reason? The paint will look different over the prier and the mud(if not also primed).

Primer goes on after all mudding. He will need to prime again when the last muddling is done. At the very least, all last coat mudding will need to be primed as Handymac said.

In addition to the primer needing to end up ON TOP of all the drywall and mud, it's a royal pain to sand compound if it's been topcoated with primer or paint.

You can probably find the correct finish here.....

http://www.bing.com/search?q=procedure+on+finishing+drywall&qs=n&form=QBLH&sp=-1&pq=procedure+on+finishing+drywall&sc=0-30&sk=&cvid=32605032DE39471C9545281C4F085746