On March 6, 2018, the Marriott Rewards annual category changes will take effect. According to Marriott, 74% will stay the same, 21% will move up and 5% will move down.
Will this affect that redemption that you have had your eye on? If it will affect you negatively, you should act before March 6 and book your rewards redemption. After all, you do not need the points In your Marriott/Ritz Rewards account to book award nights. If the amount that you need to redeem for your award will decrease after March 6 (wishful thinking), you should wait to book your reservation.