This could be fun. Voldemort was defeated in 1998 by the way... so 19 years after 1998 is actually 2017.
But if you go by school years... the 97/98 school year is 19 years before the 16/17 school year. So I suppose you're right in a way.
But I'm fairly sure the '19 years later' epilogue related to 19 years after Voldemort's death plus a few months, rather than the beginning of the 2016 school year, which is in fact only 18 years and a few months.
Oh well... who cares
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My character is the son of Dudley Dursley and his wife. He was born in July 2005, which makes him 11 for the start of the 2016 school year.
Awesome.
I'll leave you to accept/reject the character. It's courtesy really.