Go into practice mode and set the opponent to jump (either blocking or not, depending on the advantage you want to test). Hit them with an attack that you know the advantage of, such as a standing 3 (if testing block advantage, wait until they are on the ground so they can block it before jumping). As soon as the attack connects, hold jump so that you jump as soon as you recover and your opponent will do the same. Note the difference in timing. If your standing 3 is, say, -2, this will give you a good idea of what that difference in jump timing represents. Once you get a good feel for this, you can start using jump timing to make educated guess about unlisted advantages, such as back-ground-bounces and interactables.