I would say don't smoke anything beforehand for two reasons:

1. If you smoke while cooking, you might accidentally lose concentration or something and burn the cannabutter, which sucks because burn up the weed to no effect.

2. There's nothing like the first time eating, you'll be watching TV or talking to your mates and all of the sudden realize, "oh dear christ on a cross I am ripped off of my TITS!" It's a really fun and unique experience, so don't smoke the first time.

Afterwards is ok, because it can get old waiting for them to kick in (sometimes up to an hour and a half)

Good luck!