How Long to cook a 20 lb turkey?

It is not frozen and I am not using stuffing. Also how long should you defrost it for? I left it out a whole day in room temp and it seems defrosted but is it? I put it back in fridge now but not sure if i should leave it back out again tomorrow...It's tuesday night and thursday is turkey day. Also I am using a er sage rub...if u have any other ideas i would love to hear them