Math is hard

I noticed yesterday that my smoke-free counter was getting ahead of me – the original code would have made today the three-week mark, which it is not. I quit on Friday the 13th, so 21 days has to be another Friday, no?
Perhaps it has something to do with the leap year…
Anyway, this morning I went to Dynamic Drive and found a better code that seems able to count. While it would be nice to say it’s been three weeks, it hasn’t.