wouldn't it be better to pause until the date has changed or a big timeout has passed (i.e 2 minutes) ? (current bypass with scripts is to wait until system year is at least 2019)
Better than what? I'm currently relying on an nvram flag that gets set by ntpd itself, you can't get any more reliable than that.
Checking the system date is a bad idea, as the default start date changes between models/firmware versions. Scripts should all rely on the nvram flag being set rather.