Not long to go ...
This totally chaotic event has its particular norms and rules of behaviour despite the fact that it seems something wild and out of control. There are certain facts to keep in mind before you go in at the deep end on your first run.
The daunting step of entering the Arena is not just a question of jumping over the fence at any old place along the route. You should look for an official "gate" either in the square at the Town Hall or in the square of the Mercado. The streets where the running takes place are cleared of people during the final hour before the start of the run. The local municipal police are responsible for this task and they won´t have much tolerance for anyone climbing over the fence any old way. Look for a proper entrance point. (A piece of useful information: be careful, by this time the local police is not in the mood for jokes).
Making the run on a drunken spree is totally out of order: It´s just plain stupid and a danger both to yourself as well as to others.