Hi all i have been away for a while but im back i have a short storey i will put up in a minute

Hi folks I am new to writing I have put up the first chapter of my book and would love some input from experienced writers.  I have a plot in my head for the rest of the story, that will unfold as we go along.  but I have one question.  at what stage do I need to introduce to the reader the villain?  I was originally going to be two thirds of the way through the book before the hero discovers him, but I think the readers will put the book down before then if I don't.