I booked every night at the same time with the idea that once we have a better idea of onboard activities, we could change a few nights either by going to an alternate venue (SD, buffet) or changing the time, particularly on Port Days with a later return time.
Also, 5:00pm is a bit early even for us. Your post I was responding to said "earliest times" not 5:00pm exactly. We're booked for slightly later than that.
Anyway, I think Princess trying to guess which dining we'll want now that there are new choices is a bad idea. It will make what is going to be messy even messier IMO.