How to bake extra turkey legs along with a whole turkey?

It's hard to say exactly, it depends on the size of the turkey and the size of the extra legs, and whether the turkey is stuffed or not. I always cut the legs off my turkey so they don't dry out, they take between 1 and 1.5 hours to cook. I usually let the turkey bake for an hour before adding the legs, then I start checking the legs' temperature an hour after that. This generally means the legs and turkey body are done about the same time. I'm usually roasting a 16lb (7kg) turkey though, if yours is smaller you'd probably want to reduce those times somewhat.