Hey there, welcome aboard!
By default, all matches for 6v6 are scheduled for 9:30 Eastern every Saturday. However, that’s really more of a suggested time. Teams have full control over when to play their matches. There’s a fully featured schedule system built into TFCL, that allows for teams to choose a new default time and day for every single match. When one team submits a schedule change, the other team will need to confirm or deny the proposed change within 24 hours, or it’ll be accepted automatically. Once a schedule is accepted, it basically becomes your new default time and day.
So yeah, schedules are definitely flexible. In fact, they’re designed that way. 😀