Nationals Because I Can; Question

Folks: Last July I sustained an injury while swimming open water not far from shore. It involved a motorboat (piloted by a person unknown to me) in a place where it ought not have been, and came very close to removing my left foot. Bad. (I will refrain from any more narration.) Four months of recovery, and I was able to reenter the (chlorinated, indoor!) water in November. I finally started swimming with regular frequency this year, and had a very good January. But travel and other things badly curtailed my ability to swim in February and March. I decided to swim at Nationals, yet can only make Sunday. That's okay. I am swimming simply to celebrate that I CAN. That said, I would like to do as well as possible. So here is my question: I am swimming the 50 fly and 50 free on Sunday. I have four weeks to be ready-ish. I will have 5 swims in this week. So frequency up, but feeling a bit sluggish yet. How would you prepare to swim a couple of all-out sprints in competition from an improving aerobic base with a month to do it? This is a low stakes question, as again, I am doing this because I can, not because I expect PBs. Have swum nationals before, and I am generally a sprinter (swim free, fly and IM in most meets). Thanks for any suggestions!