So, this might be the blind leading the blind here, but I'll give it a shot. I just posted my first thread myself, so I can't claim to know much more than you do, nor can I offer "seasoned" advice. I'm in the transition period, too. I think it's hard to identify as "poly" until it's brought up in front of you and you have time to consider it. I think society tends to instruct us towards monogamy. Taking the plunge into a poly relationship goes against most if not all of what we've been conditioned to accept as the "norm."
I have a bit of a problem with this "primary" vs. "secondary" thing. I mean, of course I understand where the language stems from. I just think it can be counter-productive. If anything, it seems logical that the "secondary" relationship should initially take more time and attention. After all, if two people are open and comfortable enough to explore polyamory, I'd hope they were secure in their love. New relationships, contrastingly, take work. I think the ideal would be to let the new relationship develop as it will, and to strive for equality.
I'm having an issue with timing, too. How do you make time for a new relationship when you're already in one? I offer you my solidarity and empathy, friend.