When to tell DD going to WDW

[cinderelladad]

Me and my DW have been debating for a while when to tell our DD that we are going back to WDW. And we are looking for some feed back from fellow DISers'. Here is a little back ground we went last X-mas time and got free dinning to go back in Sept. I want to wake our DD the morning we leave and surprise her, and my DW want to tell her a few days before so she can tell people. I think it would be cool to let her call people at the airport. We need help???