Well not saying 100% positive because that isn't possible haha. Just don't do it after a bad day or if you're pissed about something.
Made that mistake and it was a horrible 5 hours.
It is possible to have a bad trip off of one gram, but if you are in the right environment (people you trust, place you feel safe, ect..) it will be less likely to happen. Just go into it with a great mood and everything should be fine. :)