I have not heard of this issue before, but it could be a couple different things:
1. On the calendar settings page (on the WP dashboard), make sure that your automatic calendar start date is set to the date you want;
2. It may be a plugin or theme conflict, so please rule this out by following these steps: http://help.time.ly/customer/portal/articles/782129-do-i-have-a-theme-or-plugin-conflict-
3. It may be something to do with your permalinks, but in order to be sure, please submit a ticket to email@example.com and provide a link to your site so we can explore this further. Ideally, please also submit your WP admin access.