I would advise against choosing a party as your setting if you are not 100% comfortable with shrooms. I have a lot of psychedelic drug experience in my resume and shrooms are among the few that pretty much always kick my ass (but in a good way). They are also among the most visual of tryptamines, IME.
If you have little experience and your last trip was unpleasant, you may feel stressed about having another "nasty trip" and just that could ruin the whole thing, especially in a high stimuli environment such as a party.
I would suggest that if you must consume something at the party, go with something a little less chaotic, maybe an entactogen (MDxx). As for the shrooms, I encourage you to experiment with them in a relaxed setting until you feel comfortable with their effects.
Have fun!