The official change will occur at 7.30 PM IST (6 AM Eastern Standard Time).
In the U.S., clocks change at 2:00 a.m. local time.
In spring, clocks spring forward from 1:59 a.m. to 3:00 a.m.; in fall, clocks fall back from 1:59 a.m. to 1:00 a.m. In the EU, clocks change at 1:00 a.m. Universal Time. In spring, clocks spring forward from 12:59 a.m. to 2:00 a.m.; in fall, clocks fall back from 1:59 a.m. to 1:00 a.m.
In the United States, Daylight Saving Time commences at 2:00 a.m. to minimize disruption. However, many states restrict bars from serving alcohol between 2:00 a.m. and 6:00 a.m. At 2:00 a.m. in the fall, however, the time switches back one hour. So, can bars serve alcohol for that additional hour? Some states claim that bars actually stop serving liquor at 1:59 a.m., so they have already stopped serving when the time reverts to Standard Time. Other states get solve the problem by saying that liquor can be served until "two hours after midnight." In practice, however, many establishments stay open an extra hour in the fall.
In the U.S., 2:00 a.m. was originally chosen as the changeover time because it was practical and minimized disruption. Most people were at home and this was the time when the fewest trains were running. It is late enough to minimally affect bars and restaurants, and it prevents the day from switching to yesterday, which would be confusing. It is early enough that the entire continental U.S. switches by daybreak, and the changeover occurs before most early shift workers and early churchgoers are affected.