Hi Huntley, early spring isn't always the best time of year because the temperatures may still be quite chilly and rivers in flood or flowing quite strong. Thats said, you can target Garrick in the estuaries, Touws river at Ebb & Flow have mostly small Garrick and if you want to target some better fish you can go to Island lake (need a boat or kayak) or Swartvlei/Sedgefield.
At Sedgefield (and Knysna) you can target grunter on fly but September is probably a bit early for them, although some of the fish are definitely resident (become quite dark in colour whilst ones from see are more bright and shiny). In the ocean you can target kob and shad, mostly on spoons but it's not an easy task especially if you don't know the area and conditons. I would say time better spent in the estuaries/lagoons. Lures, small (9-12cm) stickbait poppers for Garrick and normal grunter flies and lost of patience will work.