I am not going to give complete details of this dream as I believe it better that people get their definition of the mark of the beast from the Bible itself rather than from me.
I also want to direct people to Mark 13:32 - "But of that day or that hour knoweth no one, not even the angels in heaven, neither the Son, but the Father."
My wife had this dream prior to us having any children, probably around 2014 to 2015. I didn't take much notice of it at the time, but given the age of our children there is some reason to consider it may be a warning from God.
In any case in the dream I came home from somewhere all dressed up and said the "Mark of the Beast" is now in (This wasn't my exact words - I have modified it so people can find the correct definition of the Mark of the Beast from the Bible). In the dream my wife was looking after a 3 or 4 year old and a 6 month old (going by sight). She suggests the weather was also Spring given we were wearing cool clothes (which would suggest September through November as we are in Australia). (I am not completely sure how she came to the Spring conclusion as we would wear cool clothes for about 6 months of the year - if I remember correctly I think there was some indication that it was coming out of cooler weather).
Since we have had a child in December 2015 who is now 3 1/4, and another one who would be 6 months past its due date on 6 September this year. It was actually born a month early but as it is a prem and my wife only got the age by how old the children looked, I would expect it would look more like a 6 month old in September than August. This second child was a wanted accident in that my wife didn't feel she could handle having a second child, and I had concluded that a second one wasn't best for her as well, and we had forgotten about the dream anyway until after it all happened, so were not deliberately fulfilling any dream).
Does this give an exact date - well we definitely the dream gave us no date prior to us having any children. After our first child was born I guess we could have guessed a two year period. It was only after our second one was conceived could we break it down to 2019 being likely, but as my wife was only going by looks in terms of the age there is also some room for error. So yes we are on the edge of wondering whether the dream is contrary to what Mark 13:32 says. However there is no harm in being ready! If it passes and nothing happens then it simply means the dream wasn't from God! So let us be ready even if it does come in 2020 or beyond!
I should have mentioned that I am not sure if the timing in this dream is relevant to Australia or the US.