This directory features data that is discussed in the paper: F. Kunneman, A. Hürriyetoglu, N. Oostdijk and A. Van den Bosch (2014), Timely identification of event start dates from Twitter, Computational Linguistics in the Netherlands Journal, 4, pp. 39-52, http://hdl.handle.net/2066/135169 This paper describes a study to automatically identify the date of a social event based on tweets that refer to it in anticipation, as early as possible. This data set comprises of the tweetids that refer to 60 football events and 5 events of other types by means of a hashtag or the name of the event. These tweets were used to train and test different approaches to identifying the event date long before the event starts. In addition to the tweetids, we give the number of days until the event at the time when each tweet is posted, and the time references that could be extracted from each tweet.