A weekly feature of Torah Tidbits to help clarify practical and conceptual aspects of the Jewish Calendar, thereby better fulfilling the mitzva of HaChodesh HaZeh Lachem...

The Molad of Sivan (based on average - this is the Molad to use for this calculation, according to Tradition) was 1:27pm Israel Summer Time, on Shabbat Parshat Bamidbar, May 15th.

Most people said Kiddush L'vana after Shavuot-Shabbat. Some said it earlier, according to Minhag Yerushalayim.

Last opportunity for K.L. in any month is 14 days, 18 hours, 22 minutes (that being half of a lunation - average figures, remember - a.k.a. Nigud or Opposition, full-moon) after the Molad. This month it calculates to Sunday, May 30th, at 7:49 in the morning. This means that the last opportunity in Israel for K.L. for Sivanis this coming Motza'ei Shabbat.

This time should be adjusted for local time. E.g. in New York, last chance for K.L. this month is 12:49am. Someone in Israel who hasn't said K.L. and it is 2:00am early Sunday morning, can still say it. However, a New Yorker, 7 hours later at his 2:00am cannot say it anymore.

Follow this: Full moon actually occurs at 2:40am EDT. 2:00am is before the actual full-moon, but after the "Traditional" deadline for K.L. One cannot say K.L. at 2:00am in NY.