Starfield Direct begins directly after the Xbox Games Showcase, which starts at 10 am PT on Sunday, June 11. We're not sure exactly how long the Xbox show will last, but it'll be at least an hour. Xbox games marketing VP Aaron Greenberg said on Twitter to expect "roughly two hours of non stop games, games, games, games, and Starfield" from the events.
Starfield Direct will be streamed on YouTube and Twitch, on the same channels as the Xbox Games Showcase, so you don't have to go looking for it if you watch Microsoft's show. (Where I'm hoping to see a different upcoming first-person RPG, Obsidian's Avowed.)
Bethesda hasn't teased the contents of the Starfield Direct in great detail, but this is the biggest marketing event it'll have before Starfield launches on September 6, so we're expecting to see a substantial amount of gameplay, and some details we haven't seen before. Maybe we'll get a glimpse of what earth is lookin' like in Starfield's future?