Dianacs, I agree with all that ArleneG said. You can pretty much "write your own ticket" as far as your schedule in most facilities since the need for nurses is so great.
I've heard that most orientations are full-time for a few weeks at least. It seems like it'd be best for continuity's sake to be orienting day after day so what you learn stays with you and is reinforced each day. As a new grad, I would suggest working full-time for as long as you can, again, so you get into a routine and by repetition and practice, your days will be more organized and all you're learning becomes more natural. I've worked with new grads who've gone part-time right away, however, and they seem to do fine. For me, it took a year of full-time working to feel fairly competent and comfortable-- but that could just be me!
At our hospital, "full-timers" work 8 or 12 hour shifts, 36 to 40 hours/week; "Reular part-timers" must work at least 40 hours/2 weeks (5 days/pay period) in order to receive sick and vacation pay. Less than that is called "Part-time" which is your status if you work less than 40 hours/2 weeks, and the last level is "Casual", and they work as much as they want, but must pick up one week day and one weekend day shift/month. Lots of options are available and I wish you all the best in your career!