My son didn't lose his first until well after all of the others kids in his class. While most of the kids lost theirs in kindergarden he lost his shortly after he started grade 1 at the age of six.
I noticed my daughter's first loose tooth shortly before her fifth birthday and the two bottom ones came out shortly after she turned five. The two top ones are loose and have been for months, but she doesn't wiggle them much.
Cute story... when the fist tooth became really loose she wouldn't let us pull it (it was dangling from her gums) and as we ate supper we realized it had fallen out in her mouth but we were lucky to get it before she swallowed it! We weren't so lucky with the second one. As she munched on some ice in a restaurant one day a look of shock took over her face and I though she was choking. I noticed her mouth and asked if her tooth had fallen out and she said no. It had and she hadn't realized and as far as we know it went down the hatch with the ice. We had to write a note to the toothfairy explaining the circumstances. The toothfairy understood the dilema
and left her a little something anyways.
I have heard that girls will lose theirs before boys but I'm not sure how true that is.