Hello, I'm collecting seeds from my plants for next year too. I agree, keep checking the plants and the seed pots, let them dry out naturally. Collect the seed/seed head in a paper bag and dry them out further. For me I would sow them quite soon after collecting if they are ready.
Foxgloves & poppies have thousand of seeds. My foxgloves seeds are ready now there is going to be so many of them. I plan to snip off the plants and shake it around, and I will still be able to grow some from seed as well.
I collected some seeds of my ragged robin a few weeks ago and sowed them........I've got quite few seedlings coming through.