I just harvested some and took a few pictures. Hope this helps. I pinched a lot of the spent flower heads and only a few had seeds in them. You have to check every day, you can get lucky
This is one of my favorite herbs because it blooms for such a long time and the bees LOVE it so be careful. The plant is kind of prickly and while I am out messing with it and bees are buzzing around me every once in a while I freak myself out thinking I have been stung, but it is only the plant poking at me.
The bees make me a little jumpy