The NHL offseason officially begins following the completion of the Stanley Cup Final in June. This year, the last possible date for the Cup Final is June 24.
Offseason planning for the 30 teams eliminated before the Cup Final will already be underway by that point. The 16 teams that fail to make the playoffs will have over two months to prepare.
Some teams will only make small adjustments to their rosters. Others, such as the Boston Bruins and Vegas Golden Knights, could make big changes depending on how much salary-cap room they have for next season, how many free agents they decide to re-sign and their roster needs.