I have never started them from offsets, but after 3 years mine seem to have multiplied, so I think yours might flower in 3 to 4 years.
I love those little iris, but, boy, we have been hit with a heatwave that burned all of my blossoms. :-(
To think that we had a snowstorm 2 weeks ago:

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Depending how little they are, optimistically, you will see a few blooms next spring. Check out the pic at the link below. I'm thinking I have dug and moved offsets that size before and had some of them bloom the following spring.

I guess time will tell...please keep us posted.

That reminds me...I'm having a new propane gas tank set this coming week and need to dig and rescue the reticulatas before they come. I know the 2 clumps bloomed and maybe can tell how many blooms there were, so it will be interesting to see how big the bulbs or offsets are. I wonder if there will be a bazillion.

Sue

Here is a link that might be useful: scroll down to the pic of Iris reticulata bulb clump

I'm greatly cheered! I'll park them beside the Narcissus seedlings and see what happens to them all. Hopefully more TLC than OMG!

I also am very fond of them - particularly the wine-coloured ones. And I enjoy bucharica, as well. (I just hope it got enough of a baking this year.)

Thanks for helping.