Two quick questions

So I got a new skunk cleaner shrimp about a week ago and I was wondering about how long it takes for them to start "cleaning" the fish? Next question, I've recently noticed a singular white spot on my b&w clownfish. It's more of a three dimensional bump. Pretty small but noticeable since he's black. I'm thinking it's not ich, but I've never had ich in my tank so can't be too sure. Could it be some sort of external parasite? I know you need a pic, but the little bugger never sits still so I'll do my best to get one up here in a little bit.

 

Both of the skunk cleaner shrimp i have had started cleaning within a couple days. They would normally setup in the open on the side of a rock or in a large cave and the fish would just come to them.