Hi -
We'll be there for our third MNSSHP on 9/29. After you go thru security at MK, CM's were right there asking at 4:20(when we arrived) if we were coming for the party. The wristbanded us there and said until closing time of MK for day guests - 6PM last year, 7PM this year, we could go anywhere inside the park. After official "day" closing time, all guests with wristbands are swept into a specific "land". It's been Adventureland or Frontierland in the past - they will tell you if it's one of those or elsewhere. All day guests leave the park at this time.
As I recall, we went on Aladdin 3x, JC, PoC I think, then ate at Peco's Bill's since there were absolutely no ADR's or walk-in's anywhere last year at TS restaurants. I am guessing due to FDP, that is definitely going to be the case this year, too. After a crowded meal at PB's, we readied for the parade outside, which was then cancelled due to rain - instead we got the Rainy Day Character Caravan - or whatever it was called ! -
A few years ago, we were walk ins at LTT at 8:15 PM as we ducked in as the Boo to You Parade passed by. We had characters to ourselves practically, and asked them to actually leave us awhile so we could eat!!!
But, yes - you can do lots of riding in that extra few hours. My son did Astro Orbiter a couple of times and SM also - before 6PM. Of course, it was raining. Tends to lighten crowds a bit!
Enjoy!!! Although the event is advertised for later, and it can be a long night with little ones, ticketholders can definitely get in as early as 4 or 4:30 PM!!