Last Day of Passover ~ 22 Nisan (April 4)
Shavuot ~ 7 Sivan (May 18)
Yom Kippur ~ 10 Tishrei (September 16)
Shemni Atzeret ~ 22 Tishrei (September 28)
It is customary to light the memorial candle after sunset on the eve of the yahrzeit date.
The candle should burn at least until after nightfall the next day when the yahrzeit ends and should be left to burn out on its own.