Think about the problem from first principles.
Assume one device is the master and has the time. How long will it take it to transmit the time? What time will it be when the time has been received and saved?
Do you really need separate Arduinos or could one of them do everything?
Would it be possible to run several Arduinos from a single crystal oscillator? Then maybe you could have a common reset button to get them to start their internal counters at the same time?
If you explain the totality of your project you might get some useful advice.
...R