My Rule of Thumb is if there is any restaurant that I know I want to eat at, or if there is a specific time that I want to eat, I make an ADR.
April is busy. The Dining Plan has made all TS restaurants far busier than in the past. If you want a TS meal, either in the parks or at a resort/Boardwalk area I would advise you to make your ADR's ASAP.
Are you on the Dining Plan? If you are, you certainly don't want to find yourself in the position of having TS credits and being unable to use them as you do not have ADR's
Good Luck!