On this year (2026) that the second day of Shavuot is Shabbat, when should we daven Kabalat Shabbat?
A. Rav Schachter (Piskei Corona #37) quotes “ the Knesset Hagedola who writes that one shouldn't start the second night of Shavuot early. Pri Megadim disagrees since the reason to start the first night early is temimot to complete the days of the Omer and that doesn't apply to the second night of Shavuot. However, Rav Schachter explained that according to the Netsiv that there's a need to make kiddush of Shavuot on the date of Shavuot itself and accordingly it is important not to start early even on the second day. His conclusion is that we're not strict for the Knesset Hagedola since the whole concept here is a minhag.
Although there are Poskim how to allow making Yom Tov early on the second day of Shavuos, the custom is not to. There are a number of reasons for this. One reason is because essentially the second day of Yom Tov is not biblical, rather m’drabonon, (as nowadays we know that the first day of Yom Tov is the correct day, nevertheless we still keep the second day). Thus being the case if we make an early Yom Tov on the second day, we might prepare from the first day to the second, or mistakenly do melacha.”
Important Numbers
