For now, the best places to follow news on upcoming D events is the Announce forum, and Adam Ruppe's This Week in D blog:
DConf - 2020, was scheduled to be in June of 2020, but was cancelled due to the COVID-19 pandemic
DConf Online - 2020, happened on 21 November - 22 November.
Beerconf is a nightly gathering of D conferencegoers during the DConf conferences. It also has become a monthly online gathering since the cancellation of DConf 2020.
There are regular meetup groups in London, Silicon Valley, and other locations - please check the forums.