This is the post where I point out my errors, hoping you won't commit the same ones.
The weather, and some lack of foresight on my part, made the conversion go less smoothly than it might have. None of the errors were serious - in only 3 months I grew a nice lawn - but they have created more work than was necessary.
NOTE: My planting schedule was constrained by having plants shipped from Nebraska - I was caught between their earliest shipping date and my desire to get the plants here before the Arizona heat set in and made it risky to ship them and miserable to plant them. This will be less of an issue for anyone planning now because there will be resellers in Tucson and Phoenix soon.
Bermuda Grass Control: I should have started Bermuda control the previous fall, because it wasn't quite out of dormancy when we planted the buffalo grass. The heavy watering while the buffalo was being established encouraged the Bermuda. Despite spot spraying and pulling, there are still some thriving patches of Bermuda in the lawn. Unless the two grasses go into and out of dormancy at the same time (still unknown), I'll be able to spray the Bermuda with glyphosate while the buffalo is dormant.
Killing the existing Bermuda will be especially important for anyone who is planting plugs into an existing lawn without having it stripped of old sod. It requires several applications of glyphosate done while the Bermuda is well-watered and actively growing to get a good kill rate.
Annual Weed Control: Applying broadleaf weed killers in Arizona is controlled by the temperature - despite being for "broad-leaved weeds", the herbicides will damage turf grasses if they are applied when it's too hot. Their definition of "too hot" means spraying weeds is not an option during most of the Phoenix weed-growing season.
I should have used a pre-emergent to control annual weeds. Hand-pulling got the worst of them, but it was extremely time-consuming. Applying pre-emergent this fall and next spring should get them under control.
Soil Preparation: The buffalo grass arrived the day before the sprinkler system was installed. Again, this would have been better done sooner than it was, to give me time to let the tilled-in compost settle, refill low spots along the sprinkler tranches, and for the first crop of annual weeds to sprout and be killed.
A lawn roller would have been useful before planting to make the soil firmer, and after planting to make sure the plugs were in solid contact with the soil.
I filled in the worst of the low spots and will touch up the levelling while the lawn is dormant.
Sprinkler Installation: I forgot to tell the installers to use 6" pop-ups, which means I have to mow the buffalo grass or it starts blocking the the water distribution.
Fortunately, they used sprinkler bodies that allow me to retrofit 6" popups without having to dig up the lawn. As soon as the pop-ups are changed out, I should be able to let the buffalo grass go unmowed.