Very solid, well put together experience. I feel the timing is very difficult to get right because of the way that you're showing the countdown. I think instead of a long continuous analog bar, you should change it to a digital bar, for example a bar segmented into 3 parts. Each part disappears so like 3. 2. 1. JUMP. 3. 2. 1. JUMP. It will feel a lot better as you'll be able to feel a sense of 'rhythm' to it.