Music for the countdown
Pick something livelier than your stream background. The Starting Soon playlist is 12 of the most upbeat songs in the catalogue, around half an hour, and it loops.
The timer
Use the starting soon scene page. Set the minutes (or a clock time), pick a title and an accent colour, and copy the URL into a browser source. The same page has a Be Right Back and an Ending version.
The hand-off
The music fades out in the last seconds of the timer, so you don’t have to touch a fader. When the timer hits zero, the screen says you’re going live.
Don’t forget the credit
The scene page shows the track and the credit line in a lower-third. Keep that, and add the line to your channel description.
Questions
How long should the timer be?
Three to ten minutes. Make sure it ends before you actually want to be live, not after.
Does the scene page work in OBS?
Yes. It is a plain web page: add it as a browser source at 1920 × 1080.