Here's a little tip on how to get the vinegar to work when it's still rather cool during the day...I watered the yard early in the morning, so everything would open up nicely. Then I zapped the weeds when they were the most receptive. Ouch! By the end of the day they were brown, dry and dead as could be.
Don't forget to add a teaspoon of liquid soap per gallon, and a little orange oil will just finish them off. I used 20% vinegar and diluted it with a mix of 60% vinegar to 40% water, 1/2 tsp. of soap in a half gallon sprayer. I would normally add orange oil but I was experimenting so I left it out. I just misted the leaves of the plants thoroughly and it wiped them out.
Just remember that it will kill any foliage it gets on, so take a sheet of newspaper or cardboard to shield the plants around where you are spraying to keep it off them.
Really, I don't mind the henbit much. If you want to see a whole bunch of it, go up to McKinney and take the exit just north of 380. On the west side of the highway there are 2 or 3 large fields that look like they have a purple haze hanging over them. Almost as pretty as when the bluebonnets open up!
Hang in there...the wildflowers are coming!!!