Baby's Sleep Training, Part 2

Two nights ago, Baby slept for four hours in his crib. Four hours straight. I got up, nursed him, and put him back in his crib for another three hours. At 4 a.m., Husband got Baby up, brought him to me, and I fed him and let him stay in our bed the rest of the night because I was just too tired to get up.
Last night didn't go so well. We put him in his crib, and I watched him fall asleep, but two hours later he was up. Then he was up two hours after that, and two hours after that, until finally, at 3 a.m., I got him out of bed and gave him all night access to his food and slept fitfully until 7:16.
Today, during the day was a little better. He had the three naps that are supposed to be standard for a baby his age, and only one of them was in my arms. One nap was even an hour, which is rare for this child. When he woke up, he was smiling and cheerful, and I made a big deal over how proud I was of him for napping in his crib. I know he can't understand it, but I praised him anyway.
Tonight we put him in his crib, awake, at 9:20. I turned on the cd player and was out of the room before the first song was over. He's been in his crib for a little over an hour. I expect that we've got another long night ahead of us, and we're going to try to give Baby formula when he wakes up and see how he does with that.
I know a day doesn't indicate a change or a pattern, so I am trying not to be too excited about this. Still, I can't help but be slightly encouraged and very thankful for the reprieve he's given us.