The normal rule is to plant things out in the fall soon enough to give the plants time to establish some roots before a hard freeze, so maybe 6 weeks before your freeze date.

I just did some perennial salvia and it is so hot, they may not make it. I am keeping them well watered. I won't be doing any more transplants until our weather cools down.

I think your thistle and coneflowers will be fine as I move those two around quite a bit anytime that I want. I don't know enough about the others. Of course, I'm not in your zone, so I may not have the best advice.

I don't know about the delphiniums or vern.. I moved coneflowers the first week of June and they had transplant shock for awhile, but they are blooming and not wilting on these hot days we're having like the Kim's Knee Highs that I planted. I have found smaller plants of blue globe thistle move better than the larger ones. I have had some not make it when moved.

Sue