It's usually a good amount of time before it's loose enough to fall out on it's own, like maybe 2 or 3 weeks, however, once it's loose enough that we can see the top of the tooth (meaning the part that used to be embedded in the gum) and we can see the pulp in the center of the tooth when it's wiggled certain ways, then we pull it out. It bleeds a little bit, but nothing that a good rinse with cold water won't take care of.
My kids get $5 for the first tooth and $3 for each tooth after that. That's probably a lot more than most tooth fairies give, but our tooth fairy has a sliding scale depending on the health of the tooth. Since she uses the teeth to build her castle she doesn't pay as much for teeth with holes in them (cavities) because they let in a draft (our tooth fairy is small like Tinkerbell). So there has to be room for the sliding scale. So far she hasn't had to accept any teeth with cavities in them yet.
Our tooth fairy also leaves a pretty note in glittery marker on the occasion of the first tooth telling our kids congratulations and to keep brushing because they're doing great so far. Sometimes she'll leave them a packet of floss if they've been forgetting to floss recently.
Also, every time she visits, she comes in the window, even if it's shut (because she has magic of course) and we know that because she always leaves a trail of glitter from the window to the bed and back. We figure that it's magic dust that falls off of her wings and wand.
Also, I made my son a special tooth pillow. It's small and fits under his pillow perfectly. It's got a tooth shaped pocket in the front that he puts his tooth into. I made the pocket out of jersey (an old T-shirt) so it would drape around the tooth and keep it in place.
My son lost a tooth at his dad's house over the last summer and they LOST the tooth, so no tooth fairy visit for him there. I was PISSED! It was so careless. I mean, I've DUG THROUGH THE GARBAGE for a tooth that accidentally got thrown out when my son wanted to hold it and wouldn't go put it in his pillow like I told him to (I found it too!). So anyways, the tooth fairy left him a note next time telling him that she went back and looked for his tooth. She found it so she was leaving him the money from last time too.
I love being able to do all of this for my kids. I believe in keeping the magic alive for as long as possible! :)