So what would happen if you just used a little less boost and made it so the rubber domed to a point where you could still press it on the rubber? Rather than waiting all that time, it seems like you are just using too much boost. And I can think of several reasons why a manufacturer would want you to use more boost than you need to in their instructions. Can't you?
If, after a while you need more boost, you can just take off the rubber and add more boost. But putting the boost on, putting so much on that the rubber will keep curling off the blade so you have to wait for it to uncurl and then putting it on will waste your boost and your rubber.
When the sponge expands and the rubber is stretched, the rubber will play like it is boosted. When the effect wears off it is because the sponge has lost some of that expansion, or, the topsheet has stretched enough so there is not tension between the topsheet and the sponge any more. After boosting a certain number of times the rubber will stop having a boosted effect and the topsheet will start losing its grip from being overstretched. Then you have to buy new rubbers and you have used a lot of boost and need to buy more.
From a theoretical standpoint, if you use the right amount of boost you should be able to put the rubber onto the blade almost immediately.
From a theoretical standpoint, if you can put the rubber on the blade before the boost has fully expanded the sponge, it will keep expanding the sponge while on the blade and the blade will keep more of the boost from evaporating so the boost effect will continue to affect the sponge for longer and you will not need to reboost for a longer period.
From a theoretical standpoint, if you put so much boost on your sponge that your sponge expands to the point where you have to wait a week for it to uncurl to put it on your blade, then you are wasting chemicals you could otherwise use later, and prepping your topsheet to wear out quicker without getting the use of it. The rubber deteriorates and downgrades from the stretching. And if you just kept boosting a sponge and letting it return completely to flat over and over again, without ever playing the rubber, eventually, you would have a dead topsheet just from boosting without ever having played the sponge. Just like if you stretch a rubber band out to much and put it on something that keeps it at that length for a long time, you will end up with a dead floppy rubber band that does not stretch and recoil any more.