I had some diarrhea when I went to the second stage with Parastroy. Nothing serious but it made me a bit uncomfortable.
It was the following day so you should be fine for your party.
If you are concerned perhaps only step up the Para-Rid for the AM dose and step up both for the evening dose. Should not make any difference in effectiveness as the PAra-Sweep is for bowel cleansing (I called the Parastroy people as I simply couldn't take 6 of them a day without disaster although most people can)