Actually now is a great time to apply Grub-X. Grub-X contains Ofthanol which has been only the market only for the last few years. Ofthanol's main advantage as an insecticide is that it lasts several months once it is applied. Ofthanol works differently than the traditional insecticides like Diazanon or Dursban. Ofthanol has to be absorbed into the root system of your lawn and takes several weeks before it becomes fully effective, so the time to apply is NOW before the grubs go to work. Diazanon on the other hand should be applied when the grubs are actively feeding on your lawn, and will start to kill the grubs within 48 hours. Diazanon unlike Ofthanol is only effective for a few days.
Whatever method you choose, realize that you will only control the grub population (and the critters that love them), you won't completely eliminate them.