I don't know anything about your climate and growing season but you could move some of them and leave some in place and see how they do next year. Plants always "sleep" the first year so you should see an increase in size next year.

My wintersown plants didn't get very large either. They need time to establish themselves and grow their roots mainly in the first year I believe.

I have many plants that ended up different in size than I expected and will be moving many of them soon. My climate is different from yours so I'm not sure how well they would overwinter but I would say if they are perennials they should make it.

Northern Japan can be very cold and snowy. With the warm current flowing by, I think it must be the equivalence of the US zone 5 or 6a.

I do not like to transplant seedlings or young plants in the fall, because I found that the young transplants' roots did not have enough time to settle to withstand deep frost. Most of them ended up dead no matter what.

I normally transplant them in early spring right around the time the soil begins to thaw while the soil is still cool. Seedlings have a better chance of survival then.

I would like to suggest that you allow the young plants to go through their first winter before transplanting them. They will be much stronger next spring.

Thanks to both of you. I might pull out 2-3 of some plants that are already crowding each other and move them elsewhere, but otherwise maybe will let sleeping plants lie until next year when I see what's what. My husband even commented that we don't even know how tall they'll all be, nor what all of the blooms will be like (I got lazy in writing down what was planted where), so encourages patience also :-). I like your advice. Thanks again...