I just updated my dream at 6:15 PM. The pink and lavender sky is so pretty and I like that my streetlamp, police station and lighthouse are lit up. It's also not too dark, so it's my favorite time for an update. IMO, all of the hourly music is good...especially during the evening.
Probably 6 pm! 6 pm is my favorite time to personally update, or 6:30-6:45 pm since it's close to 7 pm and you get pink/purple skies with stars. c: And the lights are on past 6 and I really love that.