Yahrzeit (literally "Time of the Year" and connotatively "anniversary") is the anniversary of the death, not the burial. So the first yahrzeit would be observed on the first anniversary of the date of death. However, some authorities rule that if the burial takes place more than three days after death (the day of death being considered day one) that the first yahrzeit take place on the day of burial.
Yahrzeit is a commemoration of the death of a Jew by a mourner (the child, sibling, spouse or parent of the deceased). The date of the Yahrzeit, which is calculated according to the Hebrew calendar, is the anniversary of the death, not the burial. The anniversary of the death of a loved one is naturally a solemn day, and Judaism helps the mourner experience this pain and and also honors the memory of the deceased via Yahrzeit rituals.
The Yahrzeit does not come straight after the death, but on the anniversary of the death. Therefore, if you light a candle - even one intended for the Yahrzeit that burns for 24 hours - on the evening after the death has occurred, it is not technically a Yahrzeit candle. I can't see that there would be anything halakhically (by Jewish law) wrong with doing so, but I would most definitely urge you to check this with a rabbi and don't just take my word for it. There are several online "ask the rabbi" services who will be able to help you with this - I'd recommend the one at www.chabad.org as they've never let me down yet and will send a personal reply usually within a day or two.
My mother died August 17 2006 and I need a Yahrzeit calendar for that date in order to observe the Jewish anniversary of her death each year
You go to the Hebcal date converter. See related links.
The death of jesus is observed by christians the world over on good Friday.
Good Friday
One of the Greek burial rites were that some were burned/cremated soon after their death.
A chamber made for the king or queen of Egypt, after death, they are put in burial chambers.
nothing
Good Friday
entire mummification process took about 60 days, thus meaning the funeral and final burial of ancient Egyptian mummies occurred at least two months after death