It sounds more like a social network than social media, i.e the pre-timeline, pre-algorithm version of Facebook. Back when the content came from people you know rather than people you don't.

I really like the idea, it sounds like a very healthy way to engage. If you took a photo on holiday you wouldn't be able to share it until the evening, so you'd just put the phone away. It becomes a camera. At the moment I see people take a photo and then for the next hour they're distracted by reactions, comments, feeling obligated to respond to comments... they miss the whole experience. Sharing when your friends are actually online would also be more interactive.

Of course, if you're on holiday then your three hour home time window may be unusable. But then, worst case scenario, you bulk upload everything when you get home. It would be like the old days of returning from a trip and getting friends round to see a slide show - quite charming, really.