I'm not totally sure, maybe the production this year will succeed another way, but normally videos are out in the next hours after the rehearsal. For example The Roop will rehearse saturday 10:00-10:30 (oh god feels so good to say this), so let's say we can expect their rehearsal snippet towards 12:00. Maybe i'm wrong, but basically that's how it goes.
First rehearsal videos usually show the act "from the outside", filmed from the arena with no mixing just like a random live video on YT, while second rehersal videos shows a bit of the "proper" filming we'll see during the contest.