The President of Azerbaijan is elected using the two-round system; if no candidate receives a majority of the vote in the first round, a run-off will be held.
Election laws article 178 §1 sets the date as the third Wednesday of October, which would have meant the elections were held on 17 October 2018. However, the vote was unexpectedly brought forward by a presidential decree on 5 February 2018. Azerbaijan’s Central Election Commission (CEC) held a poll on 1 February 2018 on the preparation and delivery of double cabins for the voting room.
Sources and Further Reading:
Azerbaijan brings forward date of presidential election to April 11: decree
National Council of Democratic Forces Decides to Boycott Early Presidential Elections
http://www.contact.az/ext/news/2018/2/free/politics%20news/en/68860.htm/National