Their return a day earlier than expected will give them 12 days to prepare for their Emirates opener against Leicester, with next Sunday's Community Shield tie against Chelsea likely to fall too soon for Sanchez and Mustafi.
"First of all you make a really good check-up of where they are, how much they have worked during their break," Wenger said. "After, once you know where you stand, they need an adjusted programme and to see how quickly you can fit them in again.
"Of course it depends as well on what is the need in the squad, what is their quality. All of these things together make your decision. Do you put them on the bench when they are not ready [to start]?
"It is easier to put a striker on the bench than a defender, sometimes. Because in a short period they can make an impact. We'll see."