This is my own personal opinion,but i don't transplant anything when it's flowering.The fact that it's flowering tells you that it's ok,so i'd leave it till it finishes blooming.Others may not agree,and that's ok.I don't always follow all the rules and so far it's worked well for me.
kathi

Thanks for your opinion Kathi. I was thinking the same thing. I'll probably leave it until it's finished flowering. :)

Yes, definitely wait, rather wait till next spring if they take long to finish flowering. They need a lot of energy to bloom, so try to not give them more stress at this time. Beautiful plants, btw!

In my experience about 3/4 of the plants I transplant while flowering continue to flower, while the other 1/4 stops progressing and the flower stalk ultimately just dries up. So it's certainly possible that it would be fine, but I always wait if the plant can stand it (exceptions are the plants I get at Home Depot and really need to be removed from the soil brick).