Unfortunately, oEmbed information can only be fetched from public videos, and not private videos with a scheduled publication date. This YouTube feature is very useful together with the scheduled publication of DatoCMS's records.
But how can you make the two work together?
There's a little trick that you can use, it's not super handy but will do the job:
set the video to unlisted, unfortunately you cannot schedule an unlisted video to be listed
add the video to DatoCMS
set the video to private again and schedule the publication
schedule the publication of DatoCMS record together with the YouTube video
That's it! A bit hackish, but it's a way to work around the limitations of the system.