This site says:
one may not eat a meal on the eve of a Festival starting from the time of the afternoon prayers, just like on Fridays before Shabbos.
Does this mean that when Erev Yom Tov occurs on Shabbat, as it does this year for Shavuot, one may not have Se'udah Shlishit in shul after a "late" mincha (around the Friday candle lighting time?) Or, is there an exception made for Seudah Shlishit?
If not, what is the recommended method of when to have Seudah Shlishit?