Too Late for Leveling Lot?

I've been waiting to get my back yard (1/2 acre or so) tilled up and leveled. Guy didn't want to do it with it being so dry but now that it's rained a bit he's wanting to go ahead but I am wondering if it is not too late to do it this year as I am not sure I have enough time to get Bermuda seeded and grown enough before the temp changes. I don't want to have it just be mud all winter. Should I go ahead and have it done and maybe just let it go natural till the spring or would you just wait at this point until the spring to do it all at once. Back yard is a bitch a this point to cut with the zero turn with all the bumps.