The ideal time varies a bit depending on the server, but I have never failed to make a character at around 3 AM EST. This is because the number of players logged into the game is severely lowered compared to...any other time of day.

What I recommend is just designing your character, saving the character design (which the character creator allows you to do), and coming up with the name you'll use. Do all this beforehand. Then, wake up at 2-4 AM EST for just the 5 minutes it will take you to log in and create your character on your server with the profile you saved and name you thought up previously.

This is also what I recommend to everyone I recruit to this game. It's annoying, but it works.