Time would not make any difference.
If he was going to cash in on this fight it's better sooner then later. Wilder isn't getting any more power or speed going forward, and his craft is also stalled. Tactically there are a couple changes to make and then his odds are going to be as good as they are likely to get.
If Fury gets KTFO by Joshua this payday disappears. I would point out that if Fury beats AJ, the Wilder rematch is worth even more, but how long does Wilder wait for that smoke to clear?