practicing for primary

This little guy doesn't like Primary. He hasn't liked it since day one. It was a challenge to get him to go to nursery, until he realized that all he had to do was go, not cry and play with toys.
But now the challenge is that he is expected to sit still, listen to a lesson, sit still, not cry, sit still, fold his arms and sit still.
He has trouble with sitting still. A lot of trouble sitting still. In fact, when you go to his primary class (Kyle and I know because one of us is in there every week) Porter is all over the place. He likes to crawl on the floor and under the chairs and especially doesn't want to sit still when the teacher pulls out stickers for the kids who were good and folding their arms the whole time. He wants a sticker.
But his teacher is good. Really good. Maggie takes her time with Porter and adjusts a lot of what they are doing in class to include him. She doesn't rush and ask us to come sit with them unless he's crying. She tries to encourage instead of yelling or getting upset or flustered. She's really REALLY good with little kids. I was praying that he would get into her class (our ward is huge so there's two sunbeam classes).
But still, it's an adjustment. I was talking to one of my good friends at work the other day and Janeen suggested that I do a mini primary everyday of the week leading up to Sunday.
Couldn't hurt, right?
So we started our primary class. They are very short classes, and I'll lengthen them as he gets used to it.
It's also a very big class.
 Almost 25 members.
 Porter lines up all his stuffed animals for nursery and he's the big example of what to do.

We fold our arms.
We sit in our chair.
We don't cry.
We sit in our chair.
We listen to the lesson.
We sit in our chair.

Today our lesson was very short, about 2 minutes, and we sat on the ground. But he sat still and listened to what I was telling him. And he even corrected his animals when they were getting out of line/falling over on the ground.

At least he knows what's expected of him. Now it's just getting him to do it when I'm not watching.

I know I'm not the only one, I've had multiple people stop me and tell me so.  But I just don't know what to do about it. I hope this daily primary thing will help, but any other suggestions would be welcome.