From SOD.com:  
DAYS OF OUR LIVES will air a special episode on Friday, September  23. Co-Head Writer Marlene McPherson posted the announcement via  Twitter. "Wrapping up old storylines air [August 19]. So exciting. But  the best is yet to come- our new stories! [September 26]- with a special  episode on [September 23]. In another tweet, McPherson teased that  Salem will be in a festive mood. She posted, "The excitement is  building! Huge party with many surprises the week of [September 26]. You  are all invited! We promise you won’t be disappointed." 
In case you didn’t know, August 19th is the last day for Higley’s writing, then from August 22-September 23, the new writers will be wrapping up Higley’s storylines and ushering old characters out, then there will be a big celebration planned for September 26, where John, Marlena, Carrie and Austin will be at. Matthew Ashford’s first day will also be in September, but Jack may not be at the celebration and may be held captive somewhere.