Usually an SNTP client will add the latency/2 to get the correct time - I.E. if a packet takes 350 msec to return, then you'll want to add 175 msec from the wal

Usually an SNTP client will add the latency/2 to get the correct time - I.E. if a packet takes 350 msec to return, then you'll want to add 175 msec from the wall-clock-time in the packet to get the "current wall clock time".