I'm the same way when it comes to knowing about plans ahead of time. I start filling my head with all these "what if's", start feeling sick, make up some lame excuse as to why i cant go, and then end up spending the night at home missing out on the all the fun! When i do actually end up going out i will always 1) drive myself to where ever we are hanging out (so i can leave if necessary) 2) show up after everyone has already arrived (that way i dont have any commitments to drive anyone home if i start having one of my attacks) 3) Always have an excuse if you do feel the need to leave early(have to study, have to work early, didnt sleep well the night before etc.) By having the option to leave if i need to makes me feel a little better about going out. But when i do find myself getting worked up right before im suppose to leave i will try breathing deeply to relax and while driving to the event i try singing out loud to the songs on the radio, and once im with my friends i usually end up having such a good time the anxiety actually takes the back seat for a couple of hours. Hope this helps. And im sure you will have a blast with your friends tonight!