I'd suggest you go ahead and divide/replant now, unless you'd be crushed by possibility of fewer blooms.

Don't wait. Plant them now, they will be fine. They will not live until next October.
Renee

They're still in the raised boxes; I haven't dug them yet.

NEW QUESTION: I just found this at the Greenwood site:
In Southern California, rhizomes (swollen tuber-like roots) should have 1/4" to 1/2" of soil covering them.

I thought the rhizomes should be exposed except in areas with extremely hot temps (e.g. Phoenix area). I wouldn't call my area "extremely hot". What do you think?

Growers have been experimenting with this. Rick Tasco of Superstition in Cathey's Valley, near Mariposa, plants his slightly beneath the soil, and so do a number of other growers across the country, and they all report good results and fewer losses. It is now understood that rot comes from a bacteria that gets into the rhizome through wounds or cuts, not from burying the rhizome too deeply. I am going to try it next year.

Thank you, Renee. That makes a case for letting them sit in the shade to dry out for a couple of days (as I asked about in a different post). Instead of burying the rhizome deeper, I wonder if the same could be accomplished by lightly covering the rhizome with compost while also adding compost around the plant.

I'll let you know. I did that in my "proving grounds" bed. All of the new irises that I have no place to plant are going into one bed, and I had planted them shallowly, as usual. After reading the stuff about 1/2 inch of soil over the rhizome, I threw some compost over them. If they all rot I'll let you know.
Renee

Good luck, Renee! I hope they don't rot. After reading everywhere else to not cover them with mulch or anything else (except in cold climates), and then seeing this one statement to cover them in So Cal, it makes me wonder which one is correct. And to add to the confusion there are many different climate zones in SoCal -- the cool beaches, the cold mountains, and the hot inland valleys.