Ok. For argument's sake let's say that the fee that will be enough to get him is 50m.
Wolfsburg's preferred outcome remains to keep the player, but if their hand is forced, they'll take 50m.
The window shuts at the end of this month and in Wolfsburg's position, I would be spending that time doing everything I could to keep him. Even if that 50m is there on the table, they dont need to accept it right now. They know we want him and won't go away (but hey, if we do, that's a bonus).
In their position, id be spending between now and September doing everything I could to persuade him to stay. Maybe prepare a new contract, maybe try and convince him that if he stays with Wolfsburg one more year, he could be the main man at Bayern in 12 months. If it doesn't work, then they'll grudgingly take the cash.
In short, I'm not sure that offering the final asking price (which we may have already done) would make the deal happen any quicker.