Search the forums for brooks threads, there's tons. They'll give you advice on how to break it in.

Before you start chopping you might want to break-in the saddle. Out of the box, you should notice at least a little bit of a comfort gain over your old saddle. It may not be like, "Wow!" but you should noticed something. Only after it's broken in will it be extremely comfortable.

Also, I'm not a fan of chopping up a Brooks. If you got a B17, leave it alone. It's a classy saddle. Don't cut the skirts off, it's really easy to **** it up and no one's really going to be fooled into thinking it's a Swift or Swallow.