A lot of the bloom is finished now, and I was thinking to divide the plants.
I would think that it is no big deal to do so and the timing would not matter so much As long as they are after transplanting and divided, watered well and for a week or so.

Would this be correct.

Note the plant is in full bloom, so sometime in winter to later winter, earliest Spring - before new foliage has begun to emerge. And of course you've removed all from the previous year to enjoy those flowers, which you would now be cutting off to divide....

I'm in a very forgiving climate and while I would use Dans method for my most special plants, I might be tempted to divide later in Spring some of those that are more common. I don't know about July though, and tomorrow it is July...