TOP-1369: set epoch offset once per session
Set the delaypoly seconds_after_epoch value once per session. Also use the number of seconds since TAI_2000, as we're using SPS packet version 3 in the CNIC-VD config.
Set the delaypoly seconds_after_epoch value once per session. Also use the number of seconds since TAI_2000, as we're using SPS packet version 3 in the CNIC-VD config.