He has special permission to arrive late as he continues to recover from the broken shin that has kept him out of action since January.
Zungu did travel to Portugal last month to meet with club officials and sort out personal arrangements.
Guimaraes, who had a disappointing last season, held medical examinations over the weekend and on Monday begin their first training session under new coach Pedro Martins.
Zungu, who moves from champions Mamelodi Sundowns, is expected to be able to join in with full contact sessions in the coming weeks but it is doubtful he will be ready for the league kick off in August.
He joins fellow South African Thibang Phete at the club, who are on the verge of signing Nigerian midfielder Mikel Agu on loan from FC Porto.
