If the schedule deviation is a one time occurrence for just one day, there is no need to notify the FCC. Instead, get a signed agreement between the timeshare partners and each time share partner should keep that agreement in their station records for at least two years. The station logs of the affected stations should reflect the changed sign-on and sign-off times on that day.
For all reoccurring time share modifications, the changes can be made first however Form 319 must be filed by all stations within 10 days with a revised time share agreement attached. [§73.875(c)(3)]
REC recommends that if LPFM stations need to change time share schedules for a season (such as modified times on Friday nights during high school football season), they should go ahead and file Form 319 to inform the Commission of the revised time share schedule and to file again to change it back after the season. A one-time schedule deviation mentioned above could be used if you wish to revert back to the original schedule on "bye" weeks.