I usually wait until after a snow. This year I may make an exception though. It's cold enough out there now I figure if we had a little higher humididity we'd have a good frost. I remember finding live botfly larvae under a rabbit pelt in high school. You want to make sure those things are dead.
Yes, the botfly larvae are nasty. You can squeeze them out from under the hide like a pimple. The meat under the bot is often infected. Just plain nasty! I haven?t found one in a rabbit, but I have seen a few on squirrels. I used to start hunting squirrels in September when I lived in the Midwest, so there was no frost to kill them off.