is it too soon to ask???

I'd explain the situation to the recruiter, tell them you really want to work there, but would need X many hours to make it possible, and see what they say before you quit the current job.

I'm not in medicine, but if this was a simple Job A v Job B scenario, that's what I'd do.

Not sure if the medical world has different rules and that would be breaking some kind of secret handshake or something. but in "the real world" I've found talking to folks honestly is the best way to figure these things out and see what's available.

It's not to soon to ask about the full time position, but I would not explain about the second job conflict. It sounds like you're looking for sympathy. Just explain that you noticed there is a full time position available and you would love to work full time. Ask if there is a possibility that you could accept the full time position.

As far as your other job, don't expect them to help you out. That's not how the world works. You certainly aren't helping them out by leaving your full time position and wanting to go per diem. You're making them hire and train a new employee and that costs them money. If they don't have a per diem position, then they don't have one. Most of these facilities have a specific amount of money they can spend on staffing. Replacing your full time position and giving you a per diem spot may not be in their budget. So if you need more money, either keep both jobs or find a per diem position somewhere else and then quit.

You better ask. I know the feeling. I wanted to go PRN at my old job but they decided not to use PRN nurses anymore. I was forced to resign....

You can ask for consideration. I would keep the personal parts out of the equation, you could come to the table sounding quite needy and/or sounding entitled. That sends up a red flag right away.

At my hospital going PRN is not that easy. They have a dedicated amount of PRN slots to fill, and they don't open up often. Many nurses would prefer to fo PRN because they think they can pick up as many shifts as they want and actually work their 3 shifts a week but make more money doing it. It does work this way some of the time, but my unit has cut back the use of PRN staff because they are so expensive. They have actually asked those of us who are able to pick up one more shift per week permanently.

I would do as Ashley, PICU RN suggested.

It's not too soon. Just inform them are interested in working there full-time instead of part time and leave it at that. They don't need to know the reasoning behind it.