Clarify the time in observing silence during evenings; Gayatri Japam, Vishnu Sahasranama Parayanam, etc., are done during the evening at this time.

There is no observance of silence during the evening. Except for the Mahapradosha time, there is no observance of silence at other times. Vishnu Sahasranama, Gayatri Japam, etc., can be recited.
During Mahapradosha time, Gayatri Japam should be chanted silently mentally. Vishnu Sahasranama should not be recited.