You should hear four distinct

sounds as you perform the four movements. The last two techniques,
the low block and the fist attack should not be simultaneous but a
split second between them. The whole technique should only take a
fraction of a second to execute once you have mastered the movements.
Do it as many times as you like in order to learn it correctly.
Then do the whole practice on the other side.
Once you have mastered both sides you do five on the right and five
on the left not stopping to change direction. This of course leads to
your attacker being able to attack at any time on any side with you
blocking on either side. Once you have mastered this then you start
to move around as if your attacker is really trying to attack you from
any side with you blocking on any side, still using the two punches.