well, i'm not finished with my town yet, so i just update it every day for the 5,000 bells. i do it at any time, but usually in the morning when i have nothing else to do in town.
I used to update it every day at night because I like the music, but now I try to update it right before it starts to rain, no matter what time it is. If it's a storm, all the better.
I update my dream town on a specific day and time. With that being July 5th at 5am. Its the only day that I know of where the hydrangeas are in bloom and its raining at 5am. I love the look of the hydrangeas and the 5am music when its raining.
I do prefer to update Bevelle around 8pm, the music is nice and relaxing and all of the street lights are lit up
None of my other towns have their proper DA's yet, but when I do start updating them I will likely pick a time of day where the light and music match the town nicely
Most of the dream towns I really like have the music and time of day to match the theme of the town... I think it just adds a nice little touch
When i release my dream adress it will be at 5:57 PM, so all of my illuminated projects will go off. also 6 pm is my fav time of day and has good music! for my second town that will be in morning (its a fairy themed town.)
I don't have a specific time but
On zebilage I like it when it's day because it's a zoo
In lovely I would like it sunrise because of colors
And purely in night because of forest