Probably not something that most think about but today I was looking at peonies and noticed that some had bees and some did not. You can look where the bees are on the flower to see if they are gathering nectar or pollen. The most active bees were going after the pollen. That tells be that the pollen is ripe/can be used for breeding. The same should be true for the carpel.
What peonies are your bees most attracted to? Both of mine were whites that came to me mislabeled but since they draw the bees, especially honey bees I keep them.