Cool.
There's an old martial arts adage about "emptying your cup".... I really think that saying applies big time to Bjj. Don't go in thinking you're hot ****, because you're going to suck hard for a very long time. When you think you're getting better, something (or someone) is going to come along to make you realize you suck again. You're going to get subbed by big people, small people, women, kids, old people, etc. Unless you're in competition, tap quickly and tap often. Don't take it personally, don't take it as a defeat, take it as a learning experience and get better. If there's an opportunity to roll (spar), take it, because everything you're learning doesn't mean anything if you're not learning how to apply it.
Also since you're a husky dude, don't be a mat bully. It will not work out for you, trust me.
In the end, just roll with it (pun intended), have a good time, and ask a lot of questions. Don't let your personal ego get in the way of enjoying a wonderful martial art.
Good luck.