Hullo and welcome to both!
Quite recently, Tonberry posted some excellent questions to ask a new squeeze in a polyamorous relationship if this is your first introduction to the lifestyle. Check out Myrddin's 'What could *possibly* go wrong' to find them (I'll not post the link since being basically computer illiterate, I don't know how
There is a lot of stuff to read on primaries, but my primary is basically the girl I share house, bed, pet, finances and food with. It's more a practical distinction than anything else. And yes, in NRE stages the established relationship usually has to take the back-burner for a while.
As for time; nothing beats good scheduling! I like to know when I'm going on for a date stuff like; 1) how long it will last, 2) will there be sex 3) will there be sleepovers and at whose place (toothbrush considerations). That makes multi-partner scheduling much easier. Also, if you make a commitment in the form of a date, keep to it! Nothing alienates a partner as easily as constantly making changes as to when and where and for how long you are able to see them.