The most avid Harry potter fans are the ones who literally grew up with the characters.
We're talking about those lucky millennials who went to school when Harry, Ron and Hermione did... had their first kisses (and rejections) when they did... didn't slay dragons when they did, but read about it...
And those fans will remember that the books end 19 years after the first was published. The gang are at platform 9 3/4, sending THEIR kids off to Hogwarts. N'aww.
Maths whizzes will know this took place in 2017... which is RIGHT NOW, BABY.
In Chamber of Secrets Nearly Headless Nick celebrates 500 years of being dead. He has a cake that states he died in October 1492 - thereby setting Chamber of Secrets in 1992 to 1993.
The Battle of Hogwarts is set near the end of Harry's seventh school year (1998), and 19 years on from that is... 2017!
Hear that?! You're basically living IN the Harry Potter universe for the next year! What could be more magical?!
Your Hogwarts letter turning up after 19 years of being lost in the post, perhaps, but don't worry about it, J.K...