Season 7 of Fortnite is set to launch tomorrow and Epic has detailed the release date and time for the start of downtime.
Season 6 will conclude at 1am PST on December 6 and downtime for the 7.00 patch will begin immediately after. Patch notes detailing any new weapons, map changes, or gameplay alterations will be released by Epic as soon as downtime begins.
In past seasons, downtime between updates lasted about an hour, but updates between seasons are typically longer.
Any replays saved before the update will be rendered useless after downtime concludes. Unlockable styles for outfits from the Season 6 Battle Pass can still be unlocked in Season 7 as long as the base skins were unlocked prior to the new season.
Source: IGN.com Fortnite Season 7 Downtime and Patch Information Detailed