After the sack (in 1631) of Magdeburg for how long did the imperial army stay in the city? Did they leave a garrison behind?
Tilly who led the forces in Magdeburg later led them on July 22nd against the Swedes at Werben. That's about 130km, so they would need at least 4-5 days to reach it. So that would put it between May 21st and July 17th. That's still pretty wide.