Is it to late to divide and transplant Iris?

I have divided them at most anytime of the year. Most likely if you divide them now and transplant they will not bloom this year. If you wait until after they bloom off this year and transplant soon after, I have had them to bloom the next season.

I am told, as a general rule, bulbs should be divided at the time opposite of which they bloom. If you have iris that bloom in March, September would be the ideal time to divide them.