An SE [day starts at 00:00 UTC](http://meta.stackexchange.com/questions/27199/when-does-a-day-start). I am not sure if you, or anyone except diamonds or moderators, can check a user's visitation activity log. This issue has caused some confusion for [other users as well](http://meta.stackexchange.com/questions/24884/what-are-the-exact-requirements-for-the-woot-enthusiast-badge/24888).