https://www.cnet.com/news/apple-march-25-event-how-to-watch-what-to-expect-tomorrow-streaming-service/

Preshow start time: 9 a.m. PT, noon ET (See the start time where you are)

Start time and where to watch: 10 a.m. PT, 1 p.m. ET (See the start time where you are). What the live video feed of the event on Apple's website.