HS, now would be a good time to mow the dead grass so you allow sunlight to the wildflower seedlings. Bluebonnets come up in the fall, so they are already there, just be careful to make as few passes as possible so the young seedlings don't get bruised. I like to use a regular lawnmower in the early springtime because the turf tires are not nearly as abusive as my tractor's tires.
Whatever wildflower you have, watch the stems closely for buds. Once the buds form, all mowing must be stopped. It's easy to see the buds form on bluebonnets, but may be less obvious on other wildflowers, especially Indian paintbrush. In my area, I don't dare mow after mid-march, but in your area it may be much earlier because of average temperatures in your area being much higher than here in N. TX.