IMNAIPL, but, now, my take on the date in a Copyright notice is to do something like:

# First Edition: Copyright 2014, John Perl Coder
# Revised 2017:  Copyright 2017, John Perl Coder
[download]

I have seen very similar notices in books I have read, so may be a reasonable way to cover potential loopholes.

Again, consult a Copyright lawyer