The start time of the maintenance window.
This string is of the format: \"{day-of-week} {time-of-day}\".
\"{day-of-week}\" is a case-insensitive string like \"mon\", \"tue\", &c.
\"{time-of-day}\" is the \"Time\" portion of an RFC3339-formatted timestamp. Any second or sub-second time data will be truncated to zero.
If you set the read replica maintenance window to \"\" or if not specified, the read replica is set same as the DB system maintenance window.
The Maintenance Policy for the DB System or Read Replica that this model is included in.