The supervisory board of the Berlin Brandenburg airport has set a revised date of October 2020 for its opening. This is nearly a decade after the original 2011 planned opening and follows years of mounting delays.
Berlin Brandenburg was developed to replace both Tegel and Schonefeld airports in the city. However, things have not gone to plan.
The schedule is authoritative and reliable.
Collected and summarized from the source below by Giang Tan
http://www.breakingtravelnews.com/news/article/berlin-brandenburg-airport-aims-for-october-2020-opening/