Network time is unreliable. I would recommend the official time from a site like NIST's Atomic Clock.

The cool thing about atomic syncing is that the watch will sync independently, but will match everything else synced to the second. No need do anything. It just works.

Like I said, it is a nice feature, and I think it is quite amazing. Just read about it. The clock will take over 300 million years to lose a single second.

To sync to this is perhaps worth checking out. The best Swiss Made movements boast of not gaining or losing more than a few seconds a month as the highest standard (under ideal conditions), a typical quartz watch will not lose or gain more than a few seconds a year, and the atomic clock will not lose or gain a second for over 300 million years.