It was something I was considering doing, especially as I pick up signing quickly, and for places like court you get paid a lot. I'd certainly learn it, then decide if you still want to be an interpreter later.
There's a lot to consider, including getting to know the Deaf culture, but you'll find that out as you learn. And if at the end of it you decide you don't want to pursue that path, well, at least you've learned a cool language!