Specific project timesheet restriction:
 - Project > Configuration > Projects > open project > enable "Use timesheet restriction" and set "Timesheet Restriction (days)"

Global timesheet restriction:
 - Timesheets > Configuration > Settings > enable "Use timesheet restriction" and set "Timesheet Restriction (days)" (note: it will only apply to newly created projects)

Ignore user timesheet restriction:
 - Settings > Users & Companies > Users > open user > Technical: set "No Timesheet Date Restriction"
