Not using a pre-emergent to prevent weed growth in a new lawn area is a major mistake, especially in Phoenix. The abundant water has encouraged astounding numbers of weeds to sprout. Arizona's warm-weather weeds are mostly waxy-leaved like spurge, or fuzzy-leaved desert plants, and herbicides aren't absorbed well. Most of the weeds barely slowed down when I sprayed them with a broad-leaf weedkiller.
Most broad-leaf weed killers can't be applied to turf grass when the temperatures are above 85°F, which happens really early in the morning in Phoenix. Some herbicides specify that the daily maximum temperature can't exceed 85, which makes them useless here.
I'm hand-weeding, which in a way is good, because in the course of pulling the broad-leaved weeds I find a lot of small surviving Bermuda grass clumps that are coming from the deep roots. Left alone, these would be huge and well-rooted in a couple of months.
The buffalograss is thriving despite the weeds. The plugs have turned into dense clumps the size of dessert plates, and there are only a few patches of dirt the runners haven't reached.