Hey I am not an expert by any means, and up here in Michigan I got Kentucky Blue grass. So different type of grass and climate. However I take great pride in my lawn. Like Pdqgp said, I would use starter fertilizer to promote root growth. Stay away from Weed and Feed for now. What you want is Phosphorus, the middle number of the 0-0-0. If I were you I would use the starter fert. now, try to plan in out to not put down anything in the summer, too hot especially in the south. Then maybe try to attack some of the weed growth in the fall, or next spring. A good plush dense lawn will crowd the weeds out.