On Shavuos night, the minhag is to wait until it is night – Tzeis Hakochavim – to daven Maariv in order to have 49 complete days. (Shulchan Aruch w/Mishnah Brurah 494:1).
Likewise, it is preferable for women to wait until it is night to light candles and say Shehechiyanu on Shavuos night. (Luach R’ Yechiel Michel Tukatchinsky, Piskei Tshuvos 494:2)
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Given it is motzei shabbos one really does not have a choice as to when to light candles shevuos night this year
Would happen this year anyway as it is Motzoei Shabbos.