Event for 'Just sent Advertising Packet'

Is there any way to trigger an event on the client when the client sends an advertising packet?  My application is sending out packets every 50ms for multiple peripherals to synchronize to, but I want the client to also synchronize to this 50ms signal.

I've tried starting timer for 50ms when the ADVERTISEMENT_START_STOP event triggers, but it ends up being out of sync.

Any ideas?