On 3/5/20 4:12 PM, Arthur David Olson wrote:
1. What's the best available statement on desirable lead times?
<https://data.iana.org/time-zones/tz-link.html#changes> says this: "If your government plans to change its time zone boundaries or daylight saving rules, inform tz@iana.org well in advance, as this will coordinate updates to many cell phones, computers, and other devices around the world. With less than a year's notice there is a good chance that some computer-based clocks will operate incorrectly after the change, due to delays in propagating updates to software and data. The shorter the notice, the more likely clock problems will arise; see 'On the Timing of Time Zone Changes' for examples."
2. In the case at hand, is changing to "on the second Sunday of March in the year after the change" sufficient?
Most likely. It depends on whether the federal change gives us enough notice. Last time it did, and I'd expect the same this time.