In the page you posted you can try setting the time directly for the value of the column by updating line 144 to be like this:
$WA_fieldValuesStr = "". time() ."";
I think this should get the time inserted into the column in your db just fine. If you are not getting the desired result for the users record then print out the update statement again to check what is being sent to the db. If the column in your db is an int type column this should work.