Store Previous date to calculate delta from today

[SheeppOSU]

I was running tests with it and I don't really see the problem. The first time you run it, you can grab the latest time, as that will be the first login. I also don't really know how you plan on running this program. You may need to use a txt file in which to save the list if the program is not always running, other than that I only did one small change to your code. I changed line 11 to the following.

previouslogindate = datetime.datetime.strptime(previousloginlist[len(previousloginlist)-1], Format)

Then if you did plan on saving the code would look something like that (I used l for short)

l = []
l = loadData()
if not l:
    l = [datetime.datetime.now()]

#code

saveData(l)

If you have any other problems I'm happy to help