Hi there, welcome.
Usually it’s good to let the new bun settle in for a bit. Since she is pretty comfortable, a week would probably be plenty of time.
For swaps, I would just swap the buns and leave everything as is, unless Sprinkles is prone to chewing blankets. If you feel like they are really sad, you could add a cardboard hideout to each area. I mean, you could move their fav things with them, but it might help to have that “other” bunny’s scent all over their fav things.
I’ve usually done swaps for about a week, some recommend up to 4 weeks. You’ll want to gauge how they react after the swap, and if they are acting aggressive towards each other through the fence. I’ve usually waited until they relax near each other through the fence, don’t mark like crazy after the swap, and I start to see their behaviors sync up (eating and sleeping at the same time, etc). Based off their relaxed behavior so far sounds like might not need too much time. 
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.