I always used to gut right after killing. Anymore though if a deer looks heavy enough that I know I'm going to have to leave it alone for a while to go get my vehicle and/or help to drag it out I don't gut.
My reasoning is with the increase in the coyote population around my area nowadays I don't want to leave any unnecessary blood and gut scent that could attract a pack of coyotes looking for a quick easy meal from a already cut open carcass while I'm gone.
As always, YMMV.
