Depends on how long he fiddles with it and how loose it is now, I have had kids who can take weeks with a wobbly tooth! I think every day someone in my class tells me thye have lost a tooth- they get so excited about it,if they lose it at school I put it in a little bag for them or stick it to a piece of paper with their name and the date on it.
If you are doing the tooth fairy work out in advance how much she "pays" I got so excited with my DD's first tooth lost I gave her $2 and this was 11 years ago! Unfortunately or me she lost her 2nd tooth the next day and I only had another $2 coin so a pattern of expensive teeth was set LOL (I know it isn't much now but then it was a lot more)