My DH and I are in the same boat, trying to make the decision about the best time to have kids. I think that having a baby right after graduation is a good idea, but there are a few things to consider if you go that route:
1) What is your source of health insurance? If it is your spouse, then go for it. But if you're on a school plan or get it from your employer like me, this may make things more difficult.
2) If you work for a year you will be eligible for FMLA, and in most cases for employer-paid sick time and short-term disability.
3) How understanding is your nursing school about absences? It's hard to predict if your pregnancy will be easy or difficult. If you miss a lot of clinical time, you might end up delaying graduation. (This happened to one of my classmates in the med tech program during my first degree.)
Good luck with your decision