The main reason to watch "In the Beginning" first IMO is that Season 1 is mostly world-building that doesn't start paying off until the very last episode of Sea

The main reason to watch "In the Beginning" first IMO is that Season 1 is mostly world-building that doesn't start paying off until the very last episode of Season 1 and then into Season 2. If you're showing it to someone you think may not stick through the entire first season otherwise, watching ItB first demonstrates that this story really is going somewhere interesting and worth your time.