Janni Lee Simner brings up an interesting thought -- Someone once said to her:
She continues with examples of well-known, successful writers whose first novels you've never heard of. Check our her Desert Dispatches blog entry about Unknown first novels and the myth of the big debut.
So, go ahead and get that first novel out there. Then write your next. and your next. and your next. Some will be hits and some will have small sells, but just keep writing to keep your writing career going.