If you want to practice speed off the floor, knock the weight down a little more still. Something you can rep 5-6 with confidence. Doing specific speed work - needs it's own session IMO - ice will probably have his say on it though. So you're going to be hitting half a dozen sets at least.
Speed is related to power - and they are synergistic to one another - get them working together you get strength. Strength = more weight, more weight = more power = infinite loop.
Thanks FF, always open to suggestions