I did one in April last year and there are several others on here who I'm sure will make themselves known. My only advice is just train as hard as you can and enjoy it on the night. As already said try and control the adrenalin, some of the others blew themselves out in the first 30 seconds. No one learns to be a boxer in a few months, the best you can hope is that your opponent has learnt less than you and hasn't trained as hard. I found the training brilliant and have continued to do it even though the likelihood of me being matched again are zero.
I loved every second but was easily beaten, my opponent was half my age, six inches taller and a much better boxer. My only concern was that I couldn't give as good a fight as he deserved, but as an experience it is unbeatable. Herol Graham was a guest on the night in a crowd of 3,500. He confirmed I had no future as a boxer but I did point out that he three years younger than me and retired 20 years ago.