3 weeks

It's pretty much happened several times in the Bible with the same reaction. Most people would not believe you but the ones who do take you seriously would probably act on it.

Tell everyone and encourage them to accept our true lord and savior, Jesus Christ

If you are the only one who knows, then I think NASA shut down. They have satellites that can detect objects in space, so humans would know at least approximately 2 months ahead of time.

Well unfortunately its not months... sometimes its days or even hours before we see it...

https://www.inverse.com/science/asteroid-gn1-2022-pass-by-earth

Ah, I see. Well, if you were the only one who knew about it, either you can see the future, or you got some real good eyesight

Its a question more about the moral dilemma of letting everyone know so they can live their last 3 weeks of their lives like its the last 3 weeks or keep quiet and let everyone carry on without panic and fear that such an announcement would surely cause.

Well either way, everyone will die. God wound up his pitch and threw the fastball. Humans would become ashes, earth broken open through the center. What's the point?

I would feel obligated to tell everyone at the very least my loved ones and word would easily spread once you do that. People need closure and an opportunity to change if they choose to.

Yea, if you tell even one person (family, friend) - might as well tell everyone as like you said, that wont stay quiet for long. I think I might wait and enjoy two weeks before unleashing the info and hence certain mayhem to follow.

Lol. Good point. Similar to me learning not to tell my kids we're going out because it's just chaos and I get nothing done.

Not telling anyone would mean that people would be living their everyday lives for the last 3 weeks, no matter how bad their life is. No one would do anything to stop the astroid, and when it hit, it would most likely take some time to kill all life on earth. People wouldn’t have any time to prepare for the worst and last week of their lives, and it would be your fault.
On the other hand, if you told people they were going to die in 3 weeks, some would panic, possibly making their lives worse. There would also be 2 possibilities if you told everyone. Either the entire human race would come together in a morbid wholesomeness to try to help life survive, or, they would start trying to tie every loose end, and, since you wouldn’t have any reason to worry about the laws, this could result in chaos, including murders, robberies, rape, anything to make themselves happy for the last 3 weeks. Then, the people who want the first possibility would have the worst time of their life, because, being to nice to commit crimes, they would be tortured for the fun of the first group.
If you didn’t tell them, people with good lives would continue living good lives, while people with bad lives would continue living bad lives.
Neither choice would end very well, but when you consider morals, it would be better to tell them. Whatever everyone else decides to do wouldn’t be your fault, you would only be responsible for telling everyone. If you tell them, the chances of the survival of the human race are higher, and you wouldn’t be lying to the whole world.

I’m not good at keeping secrets

i would tell everyone i know and urge NOAA and NASA to be on the look out. and if nobody believes me, then suck it, you can all die a fiery death and regret never listening to me.