WOL based on session activity is not the same as logging in and out; otherwise, every time you when to have tea or go for dinner and come back to your computer you would have to login again.
Obviously, you don't have to login every time you go away from an hour. At least for me, I rarely login to the forums, even when I wake up in the morning and turn on my Mac Pro; my login is still valid when I visit the forums.
It is not an issue, there are many ways to invoke a script, we do not need to invoke on login, like I said.
I will run the script on "showthread" page, so you need to take that into account and check that you only increment the day++ count IFF it has not already been incremented for that day.
You can do that in many ways.... but you cannot do it solely based on login.