I've tried striking immediately when I get a take when deadbait fishing for pike, and I've found it's not effective as a technique. I've occasionally watched pike picking up deadbaits, and they don't swallow the bait immediately. They seem to grasp the bait lightly in their jaws, often with most of the bait still exposed outside the mouth. A strike at this stage doesn't usually connect with the fish.
With deadbaits I watch the float closely, if it starts to move, or twitches, I strike after about 10 seconds