For those of you who are confused about the timeline of events between the Index and Railgun sides of the franchise (especially with the random time skips in the Railgun manga), a calendar of all of the events that have occurred in the franchise has been created by me and uploaded to the Baka-Tsuki Toaru Majutsu no Index Page.
The calendar can be reached following this link: http://www.baka-tsuki.org/project/index.php?title=Index_Calendar
Discuss both the calendar and timeline of events in this thread.