I can't remember the dates, but I think you should be ok the 11-14. It seemed like they did them all month long last year.
The event is really cute. They have characters all over the park in costume, and it is set up so that they are in one place and you can wait in line for pictures/autographs. Most of the rides are open, so you can go on rides, and they have candy stations set up all over the park, where you wait in a small line and they give you a treat. All of the stations have candy and a healthy treat to choose from (raisins, apples, or carrots). Since they only sell a limited number of tickets, it is not crowded, and you do not have to wait a long time for anything.
At the end of the night they have a little show in Sunshine Plaza where all of the characters come out and sing and dance. And the games over in the midway are all free.
I forget how far in advance the tickets go on sale, but I would get them fast, because they tend to sell out quickly. It is definitely worth the money. I wish DL would do more after hours events like this.
