Any way to check when servers are the most active?

[DoctorPepper]

The prices are out of date.

Regardless it still depicts where all the gil is.. and therefore where the majority of players probably are. I don't think you'll find a better gauge of population anywhere else official. I doubt there's been a drastic change aside from maybe some people transferring off of legacy servers and the only other way you can really figure this out is by playing the game and watching party finder which the OP said is not possible on new characters.