1. Congratulations!
2. my advice is to go interview at the hospital where you want to end up and say nothing about your pregnancy.
my rationale is:
a) it is really none of their business what is going on in your personal life and whether or not you intend to work on a full time basis or part time basis, based on some future event.
b) I think you are kidding yourself if you think you will be hired when you tell them you are already pregnant. You would have to hire a lawyer and file a lawsuit in order to get that protection.
c) landing the job and getting your 3-4 months experience before taking a maternity leave will be a chance to show them what a great nurse you are and why they would want to retain you as a PRN or part time nurse following delivery... Going in announcing your pregnancy is just going to be an X against hiring you without them ever knowing your great skills!
d) I know you have plans but again they are based on a future event. You might find out you HAVE to work full time, new baby or not. You might find you CAN'T work at all.
so go ahead and interview, leave your personal life out of it, get the job you want and then make changes as you need to. It is up to the managers to deal with unexpected glitches like pregnancies. They know about 'em, and they are used to it. YOU don't have to do the manager's job for her... LOL