Well, Lil woke up at 3 AM. A vast improvement from the 11 PM and 2 AM she had been doing. (That's in addition to her early morning feeding around 4:30-5:30 AM, which I consider normal and sleeping through the night.)
So at 3 AM, Brendon went in there and laid on the bed beside her crib. (And when he went in there, I set my phone alarm to go off in 15 minutes, knowing if she was still crying that I'd go in and nurse her.) She wouldn't calm down, but then about a minute before my phone alarm went off, there was silence. Turns out Brendon had picked her up and decided to rock her. She calmed down. Every so often she'd get squirmy, but he'd talk to her, pray with her, and do the shushing sound. (Shushing is good... comforting I guess. Sorta like white noise.) I don't think that lasted long because she did fall back asleep. He put her back in her crib and laid in the bed beside it.
She woke up a couple of other times, and I'd hear a brief cry, followed by a shushing sound. Brendon didn't pick her up again. But he'd reach his arm into her crib to scratch her back and let her know he was there. And shush.
Lil woke up again at 5, so I went in to feed her.
I think we followed the doctor's instructions decently well. And it accomplished the goal, which is good! So here's the hoping she will begin to sleep through the night again!
I should also note that if you're a parent wanting to try this with your baby, our pediatrician said he really thought object permanence was the issue partially because when she cries in the middle of the night, she calms down almost immediately when we walk in the room. If she were hungry, she'd continue being frantic. That does NOT mean that if we were to walk in her room and she calmed down before realizing she wasn't going to get picked up or nursed, only to cry again, that she's hungry. That's an object permanence thing, according to our pedi.