I thought BMGers might find this interesting and helpful. I have compiled into a single timeline various dates to keep in mind for the 2020 election cycle, including both public and party matters. My primary sources were the websites of the Massachusetts Democratic Party and the Secretary of the Commonwealth.
January 13th – National delegate candidacy forms available
January 17th – Deadline to file for DSC Senate District Caucus Seats
January 31st – Deadline to notify state party of local caucus info
February 7th – Petition for state caucus may be submitted if not previously announced
February 11th – Nomination papers available for non-presidential party primaries (may be sooner)
February 12th – Deadline to register to vote in presidential primary and be eligible for national delegate
February 14th – Deadline for petitioning state party for local caucus not previously announced
February 15th – State convention caucus window opens and deadline to turn 16 for pre-registered youth
February 25th – Deadline to register in a party to be eligible to run in a primary for state office
March 3rd – MA presidential primary and party committee elections; deadline to register to run for federal office
March 22nd – State convention caucus window closes
March 25th – Deadline to apply to be an add-on delegate to state convention
March 27th – Deadline to file candidacy statements for national delegate from congressional districts
April 3rd – Deadline to pay state convention fees or apply for waiver (except add-ons); local re-org window opens
April 4th – DSC meeting at which add-on state convention delegates and constituency DSC members are elected
April 12th – Deadline for town and ward party committees to re-organize
April 17th – Deadline to file candidacy statements for national delegate to be elected at-large
April 25th – National convention caucuses in each congressional district at 1PM
April 28th – Deadline to submit signatures to local registrars for state office
May 1st – Deadline for local chairs to return caucus books in order to be seated as ex officio delegate
May 5th – Deadline to submit signatures to local registrars for federal office
May 16th – DSC meeting at which at-large national delegates will be elected
May 26th – Deadline to file nomination papers with Secretary of the Commonwealth for state office
May 30th – Democratic State Convention in Lowell
June 2nd – Deadline to file nomination papers with Secretary of the Commonwealth for federal office
July 13th – Democratic National Convention opens in Milwaukee, WI
August 8th – DSC meeting at which presidential electors are nominated
August 12th – Deadline to register to vote in state primary
September 1st – State primary for offices other than President
September 8th – Deadline to fill nomination vacancies caused by withdrawal of nominee
October 14th – Deadline to register to vote in general election
November 3rd – General election for all state and federal offices
Thank you!