Might be late on this, but now you can manually queue stages (link) in yaml pipelines. You can then set an approval check based on the time of the day (and day of week). (instructions)

With this when you queue the stage, provided you have set a timeout for the check longer than 1 day, the stage will pause until the time has come.

We use this to postpone our release, might be unwieldy if you need to do it only once, but it's doable