As far as IF goes, I'd say go with your body's signals. When I first started low carb, I wasn't doing it at all. And I don't even think I knew anything about it, but I just began to get less hungry in the mornings. And so breakfast got later and later. Most days I was eating in a 7 hour window, but it happened naturally on its own. Now, I'll sometimes push things trying to eat in a 4 hour window.

One thing I've noticed lately when I'm in ketosis is that I feel great in the mornings before I eat. That helps me extend my fast even though I might start getting hungry. Eventually, the hunger gets more than I like and I eat.