Can I read last date of factory reset?
You can use a FirstUseDate parameter, if your CPE support this parameter.
FirstUseDate - Date and time in UTC that the CPE first both successfully established an IP-layer network connection and acquired an absolute time reference using NTP or equivalent over that network connection. The CPE MAY reset this date after a factory reset. If NTP or equivalent is not available, this parameter, if present, SHOULD be set to the Unknown Time value.