I have cuttings rooting in bags, a few are showing some roots.
when is it time to pot them? do I need to wait for the entire bag to fill up with roots?
is it better to wait for more roots or is it better to pot them before winter?
after potting, how much water does it need? does it need full sun or try to put it in shade?

many questions, sorry
in advance!

I'm no pro, and only have 1 year of rooting experience but If your going into winter as we are the Plumeria will be going dormant. I would wait for some roots to appear & then pot it. However no leaves = no water, Once the Plumeria has a decent size leaf you can start watering. But during the winter (dormant period - they loose leaves) & sit like a stick.... no water during that time. I kept mine in my back office facing east during the whole winter until spring. I'm sure someone with more experience will jump in and give a better idea of how much roots should be there prior to potting when "bag rooting" I did not attempt it that way. Good Luck!!!!

Is that enough roots to be potted?

I would think so yes.