After I complete the 25 nights for the MegaBonus promotion, I want to switch my earning preference from points to miles and start getting stays under the MegaMiles promotion. I don't want to make this change, have my 25 night stay counted as one stay for MegaMiles, and fail to get the 50K bonus points for the 25 nights under the MegaBonus promotion. Any experienced insight on the timing of when to make the change to my earning preference would be greatly appreciated.