I agree with your decision to cook the day before. Not because of leaving an unattended cooker bothers me (as long as it is done safe), but because you are not sure how long a turkey will take.
I do all day or night unattended cooks all the time without any worries. But that is with meats I generally know what to expect.
Now a turkey on the other hand. I have only done one, last Thanksgiving, and I still don't know why I haven't done another yet...amazing I'm telling you. It cooked faster than I expected, much faster. If I remember right it was a 14/15 pounder that I brined the day before, not sure but I think the brining sped up the cook too, I anticipated about 5-6 hours and it was done in about 3 1/2 -4 hours and that was at 265*.