I asked for my husband at the time to open our marriage and be poly back when I had absolutely nobody in mind. It was actually important to me to do it when there was nobody else in the picture, so that he didn't think it was just because of "that guy". Plus I doubted he would be fine with it if I liked a specific person while we were supposed to be monogamous.
There were a few people I was friends with that I started considering once we did open the relationship, but because my husband (now my ex) wasn't comfortable with it at that point, I never bothered even wondering if it would work, let alone pursuing it, and figured I would give him more time.
After a couple of years, he was the one who told me about someone he met and liked. That's when I knew it was okay to start looking at people as potential partners, and listening to my feelings about them.
In the end, he wasn't poly and it didn't work out. If I ended up back in time with the knowledge I have now, I would just have broken up right there and then instead of having that talk. But considering that I didn't know if he was poly or not and whether it would work for us or not, I'm glad I did it the way I did. I think if I had had someone in mind when I came out as poly, it would have been harder for him.