The need to slow down while you are learning has lead to some confusion. And it is exasperated by the instructions given to achieve a proper “rhythm” in the lift. For a good lifter, good rhythm is fast, faster, fastest. Fast to the knees, even faster up the thigh, then fastest during the second pull and the pull under. Your aim should be to have the bar and your body start the lift fast, and just get faster as the lift proceeds.
But that’s not how it goes with a beginner. If a beginner pulls too fast off the floor, they will miss their positions. Or, they will hit the right position at the knee, but have to slow down while pulling the bar up the thigh in order to “find” the correct position at the hip. Neither is helpful to developing good technique.
So, I tell those just learning the lifts to pull slowly off the floor, speed it up gradually as the bar comes up the thigh, then explode and catch when they feel the bar hit the right place on the hip (or upper thigh on the clean).
Concentrate on the correct positions first. Even if you have to go slow, even if you literally have to pause the bar at the knee and at the hip to make sure it is right. Then the correct rhythm, taking out the pauses and speeding up as the lift goes along, even if the actual speed has to start very slowly to maintain position. Add speed gradually, but not so fast that position or rhythm are compromised. But that doesn’t mean pulling slowly is right for a lifter past the learning stage. Ilya Ilin pulls fast right from the floor, and so should you. Just maybe not today.