She's making sure you have time to recharge your feels before she knocks you back down.
It's gonna be weird when she announces that the good news is she just finished kidnapping Ame and is keeping her locked in the basement to force her to come back fairly often. It will end cutely though because the first thing she'll do is force a duet for the ending song.
Speaking of cute but possibly emotional singing, Peo also has some coming up in like 30 minutes. It's possible it won't be sad but she adored Ame so I would be surprised if there wasn't a moment or two in there. She already sad posted a little in chat so... if you want some feels before bed just so you can wake up to Kiara punching your feels, double up!
Calli's stream is probably timed for when she figures she would be good to go after all the emotion calms down. It's probably to ease her mind and give the Myth fans a cooldown as much as it is to just keep playing a game she's enjoying though.She'll be the first other member of Myth with a chance to give her thoughts. I remember Calli was pretty calm & even when talking about Sana but she's much closer to Ame, so, who knows?
Edit: Actually since I was late to post, maybe it IS mostly for the cooldown (Herself and fans) and not so much the game itself.