There are two things you need to consider: time of seating (1st or 2nd) and actual rotation (APL, PLA, LAP).
Time of seating: This is purely a question of how late or how early you need to eat based on your personal preference/routine and home time zone. Nothing more than that.
Actual rotation: This is the tricky one and having recently opted to change my
DCL-assigned rotation (see explanation below), I am now a firm believer that the Mouse does indeed know best and you're best not to question/change his assignment. APL is for the younger set. PAL is the family set, generally with kids that are school aged or older. LAP is the adults/older kids set.
Here's my experience. I was given second seating with LAP because my kids aged 7 and 9 are considered "older". (I know 7 and 9 are still young, but when you consider that there are many little kids in the 0-6 range onboard, well age is relative.) Since I wanted to be in Lumières for our dress-up nights (the boys and my husband were in tuxes) and was one of the first onboard, I was able to change from LAP to APL.
Big mistake and one I admit that I made without much thinking. Changing to APL did put us with a lovely young family from California, but my kids probably missed out on many opportunities to meet kids their own age or older and to partake in older kid/adult conversations. We were in Lumières for formal, yes, but I think we would have preferred the company of older kids/older parents like us, even if it meant being in a tux in Parrot's Cay.
We've actually decided cruising is not quite for us, but if fate puts me back on DCL anytime soon, well you can be certain I will follow the Mouse's orders and eat when and where he tells me too!
Moral of the story: The only thing you should change is late to early or early to late, but try and keep the rotation that has been assigned to you.
Happy cruising!