I was also going to do a runner on results day; ie, run in, run out. But then my friend pointed out to me that it's best that you stay and open it there in case there are any whole year announcements they have to make, for example, last year my school sent all the English exams back for a re-mark because of the whole scandal about it. Also, if by any chance you need to change your A-level options because of your results, you can talk to your exam officer there. Alternatively, if you find that your results weren't so desirable, you can ask to know exactly what you got and how far away from a grade boundary you were so you know the appropriate approach to take, if it may be asking for a re-mark. You'll know whether it'd be worth it or not. It'd be easiest to do it all there.
But regardless, good luck everyone!