Valve set dates for 2020 and 2021 Majors
Valve have sent out an email to tournament organizers, requesting proposals for the next four Majors held in 2020-2021, in which they have set specific dates of all four events.
CS:GO's developers aim to decide on Major partners at least a year ahead of time from now on, so that tournament organizers can plan better around the two biggest events of the year.
Valve are also looking to make changes to the scheduling of the Majors, after the upcoming StarLadder Major's placement shortly following the player break was met with much criticism from the teams, with the first event of the next two years set to be held in May and the second in November.

The developers have specific dates in mind for all four Majors in 2020-2021, in fact, as they are requesting proposals for the following four slots:
May 11-24, 2020
November 2-15, 2020
May 10-23, 2021
November 1-14, 2021
To meet their aforementioned goal, Valve intend to decide on both 2020 partners by the end of June and are willing to review proposals for 2021 already, as well.
As you can see, the next four Majors will cover two weeks each – as opposed to the 2018-2019 tournaments, which were held over nearly three weeks –, reducing the impact they have on the calendar year.
To comply with the change, the organizers will have to double-stream additional matches of the Swiss stages, each of which should cover four days instead of five, according to Valve's guidelines.
In the email, Valve also reminded their partners that the Majors should be held in a timezone convenient for the majority of CS:GO customers, highlighting a 21:00 CET primetime slot, and that the Minors should take place in the same country or visa region as the main event.