Predicting the day of your or somebody else's death day is actually super easy, barely an inconvenience. The only limiting factor is if you've got a soul to offer.
And yes, there once was a person who predicted the day of his death years in advance with the combination of astrology and our help.
Although some may discredit it do to it being a suicide, those are just the nonbelievers.
The benefits of knowing when you'll die are numerous. Each breath air, each sip of water, even each bite of food will be marvelous. You'll feel way more alive than ever before.