If your weather is cold and dry, and you take no measures to keep your grafted scion from drying out, it's gonna likely fail, depending on how cold it is. You could graft now, however, then plunge the entire grafted treelet into damp sawdust in a building that that does not go much below freezing. The dampness of the sawdust will keep the scion from drying out. I much better like to use Doc Farwells grafting compound on the entire scion, it functions just like a zip lock baggy keeping the moisture in.

Another way you can gauge your fruit grafting timing is to watch similar trees in your area. If you are grafting apple stock, just see when the apples in your area start flowering or leafing. That would be a good time to graft and set out.