I think it certainly would take a while to go from seed to intro.
Back in 2016, I purchased what was supposed to be Cultivar X from a certain iris garden. In 2017, it bloomed and it looked to me like it probably was NOT Cultivar X. Emails to the nursery ensued; it was determined that the NOID was a seedling from a particular cross (actually it is a sibling to Cultivar X) and Cultivar X was sent to me in the summer of 2017. Email with the nursery in 2018 revealed that they have plans to introduce the seedling, but they are building up stock, and it might take "a year or two". The nursery's 2019 intros are up on their site, and the seedling is not up there for 2019, so maybe next year (but maybe the year after).
So, at a minimum... (I don't know when they made the cross, but this is as fast as I can imagine it going...)
Year 0 (2013?) - make the cross, collect the seeds
Year 2 (2015?) - maiden bloom
Year 3 - 2016 - one of the increases mistakenly sent to me
Year 4 - 2017 - they are still evaluating, and I discover the mistake (emails with the nursery, get the correct plant)
Year 5 - 2018 - they decide they will intro the seedling but need to build up stock ("a year or two")
Year 6 - 2019 - not an intro, so building up stock
Year 7 - 2020 - earliest possible intro (but possibly later, in 2021 or even 2022)
So that's 7 years at a bare minimum.
I don't know what the target number of plants is to have for an introduction (and you can't sell all of them, because you need some to increase for future years), and I don't know what a typical number of iris increases is (let's call it 4-6 and every rhizome produces at least that number of healthy increases, and disaster doesn't strike (weather, critters, disease)). Let's also assume that it takes 2 years for an increase to itself grow large enough to bloom and produce more increases. So with maiden bloom in year 2:
Year 2 - 1 rhizome, maiden bloom
Year 3 - 4 to 6 increases growing
Year 4 - 4 to 6 increases bloom
Year 5 - 16 to 36 increases growing
Year 6 - 16 to 36 increases bloom
Year 7 - 64 to 216 increases growing
Year 8 - 64 to 216 increases bloom
Year 9 - 256 to 1296 increases growing; can ship during summer