I have been to hundreds of concerts, including plenty of legendary must-see rock shows.

But yesterday was the concert of the year. Maybe even of the past decade.

It was my 3.5-year-old son’s first Christmas program at his little Montessori school. An afternoon work meeting went longer than anticipated and I couldn’t get there fast enough. You can’t be late to this event. The performers don’t show up fashionably late — they need to get to bed on time after the show.

The concert started promptly at 6 p.m. The first group of 15 kids are the wee ones — ages 18 months to 3 years old. A few adorable songs later, the older ones — ages 3 to 5 years old joined them on stage. Or, in this case an alter of a church.

He’s in the back row with the black striped sweater! “Can you see him?”

There is the excitement at first for every kid to find their parents and for every parent to find their kid. Mine gave me a gigantic smile and wave and he had me. I was there. Totally present and pretty certain he was going to be amazing. He couldn’t possibly blow this.

The first song was “What a Wonderful World” written by Bob Thiele (as “George Douglas”) and George David Weiss. It was first recorded by Louis Armstrong and released as a single in 1967.

Not only was the first song one of my all-time favorites, it was accompanied by every kid doing sign language. C’mon. Go easy with the sentiment. A little more subtle transition would have been appreciated. I could have cried my eyes out it was so adorable. Although my kid rocked the sign language, he displayed small, random signs of singing. Who knows what the other kids were doing…you really only focus on the one you are there to see. It’s true. If anyone says they look at all of the kids in the class, they are lying.

This is what a parent flash mob looks like.

The real performance may be the action facing the stage. The parents, grandparents, older siblings, friends, relatives and nannies that are absolutely bursting at the seams with pride create a buzz that would be hard to match. Every other arm is up with a camera recording and/or snapping paparazzi pics. Adding to the blurry concert photo collection.

Regardless of how your kid is performing or not performing, you couldn’t find more smiles. My friend’s flush-cheeked 2-year-old, dressed in his plaid button-down shirt and bow tie stood for over six minutes with his mouth open as wide as his eyes, never getting any suggestion of a note out. Yet, she couldn’t have experienced more laughter and pride in those six minutes had he belted it out.

There wasn’t any pushing or yelling out, “I love you…name”, that is so very frequent at concerts, but that was one of the most memorable music performances I have experienced. And, to top it all off, the performer ended up coming home with me.

Rock on.