I got this schedule here on TFF a few years back and it works well for me here in Centex.
Write these dates down:
Feb 15 - pre-emergent
April 15- fertilize
May 15- pre-emergent
June 15- fertilize
July 1- treat for grubs
Sept 15- pre-emergent
Oct 15- fertilize
Do the prescribed application on or a week before the dates listed. I also have St. Augustine and since following this regiment, it is as thick as carpet. I can't take credit for the dates, it is from Neil Sperry. Scotts Halts Crab Grass and Grassy Weed Preventer is the pre-emergent I use and Bonus S is the fertilizer I use on my St. Augustine. Use GrubX for treating grubs.
Thank you T bird for reposting this. I was about to rewrite it again.
Butch if you have a mix of Bermuda and St. Augustine, and you want St. Augustine, use Bonus S as your fertilizer and find a good pre-emergent. If you want Bermuda, use Scotts Turf Builder Southern for fertilizer. St. Augustine likes ot weather and water so you are fore warned. Bermuda will withstand drought conditions better if you are not into paying to water your lawn.
Stay away from the weed n feed fertilizer. Just follow the schedule above.