Nov 1st - Game 7 of the World Series (if necessary)

One Day After the World Series Ends - Players become free agents

Five Days After the World Series Ends - Free agents can sign with a new team

Nov 10-13 - General managers meetings in Las Vegas

Nov 18-20 - Owners meetings in New York City

Nov 18 - Deadline for players to accept Qualifying Offers. Deadline for teams to set Reserve List rosters for the Rule 5 Draft.

Nov 21 - Tender deadline

Dec 8-11 - Winter meetings in Orlando

Dec 9 - MLB Draft Lottery

Dec 10 - Rule 5 Draft

https://www.mlb.com/news/mlb-offseason-dates-rules-and-terms