I've had two different sites recover from manual spam actions. The first one regained all of it search positions (and even ranks better now) within one week after receiving the "manual spam action - revoked" message.
The second one received the same message, but hasn't been able to regain its rankings.
The difference between them is that first had really good links and some bad ones that Google probably wasn't even counting in the first. So when the penalty was revoked, the rankings returned as they were before.
The second though had alot of bad links. Many of those were helping it rank, so when they were removed ...the rankings went with them. But it was clear that the penalty was lifted at about 10 days after receiving the revoked message.

