I am on Brynhildr, and while not an overpopulated server, I had a few concerns because I was already getting small queue times a few weeks before Early access. When early access went live, I had a small issue with character data not loading, had to go out and back a couple times - that was from everyone logging in at once I expect, was able to change races to Viera then had 990 queue but it was less than 15 minutes to get through. I was pleasantly surprised. Since then, I've had queues of 30 most times I go to log in. I do feel for people who are on hugely populated servers, but I am not sure there is any way that Square can fix this, other than what they already do by offering free world transfers from congested worlds to new/preferred worlds. If a person on a congested server chooses not to take advantage of that, then you have to resign yourself to long queues while everyone tries to play.

You could plan ahead, and log off on another, less congest world using the world visit ability, but you would have to plan ahead... and then resign yourself to not being able to visit your house if you have one or use retainers, which is a problem.