I visualize poppers as baits to be fished "next to or on top of", next to a weedbed, next to a grass patch, next to a stump, next to a cliff and so on, on top of a submerged weedbed, on top of a hump, on top of a submerged tree, places where the fish will hide to ambush whatever may pass by.
How fast or how slow really depends on the conditions, if it 's windy and the water surface has ripples on it I prefer faster retrieves, plop, plop, plop, wait a few seconds and plop plop plop againg, while on calm days or when fishing the glass I prefer very slow and with less emphasis on the way I snap my wrist, pleep pleep and wait 20, 30 seconds or more, pleep pleep and waiting again.
At what time of the day ? many people think of topwaters as dawn and dusk baits, nothing can be farher from the truth, I fish it in them middle of the day with bright sunlight with lots of success.