By the time they get close enough to read your Kids on Board emblem, their bumper is in your bottom bracket.

Visibility at distance is what buys you time for drivers to react. I consider a half-mile the minimum. That gives them 30 seconds of texting or poking buttons on the GPS at 60 MPH.

At the rear, my minimum is a DiNotte 140R. I've upgraded to the DiNotte 300R which is easier to move from bike to bike. Both can be seen for a mile in full sun.

At the front, my daytime blinkie is a DiNotte 200L. At night, the MagicShine is the first light I've owned that gets me treated as traffic by both drivers and peds. Other lights register as "bike, eff it" and they turn or step out in front of me anyway. The MS registers as "traffic coming" and they wait for me to pass.