It really depends on where you are, I suppose. We are in the Midwest (Indiana).
Our first year we didn't really take our camper "down", and so we had to keep it "warm" all winter and only had one booking (in Jan - it fell through). The next year I listed it unavailable from Dec 15-Feb 28. We stopped having bookings around Thanksgiving and didn't see another until April. This year we have the camper unavailable from Thanksgiving weekend through end of March. We will usually have it out in March - I like to camp in it also! - to make sure everything is working. If past experience is a guide, we won't miss a single booking.