Congratulations on your development of a very popular "Nostalgia" item. Keep them coming.
I do remember school milk in primary school in the 1950's. At my school it was delivered prior to school time and distributed by well chosen 6 class girls, to the classrooms before teaching started. I don't know why the distribution was done by girls, but I was glad of it because that left us boys to play in the school yard until the bell rang. That was until one set of distribution girls left. My 6 class teacher approached me and my mate to take over for the girls, saying he thought that lugging heavy crates of milk was something better suited to boys than girls.
My mate and I had become accustomed to the girls' distribution, and thought that the job was really too effeminate for us. Our teacher was reasonably adamant though.
At about the same time, our music teacher, who was a really good bloke, was putting together a school choir. Neither my mate nor me would have volunteered for it, but the choir trial coincided with the milk distribution duties, and we saw it as a way of avoiding the girlish job of milk distribution, so we volunteered.
One morning, the music teacher was putting us wannabe choristers through our vocal ranges. He was pacing up and down across the line of hopeful singers, before stopping in front of me, listening to my (then) youthful voice for a moment or two, with a somewhat grizzled face, before announcing "M**, you are the new milk monitor!".
My mate resigned in sympathy, and we took up the job of milk monitoring as required. I have never, before or since, drank so much milk, and no one could ever explain the bottle shortages.
It was many years before I learned the reason for my choral misadventure, when my (then) teenaged kids gave me a directive " No singing, no whistling, no clapping hands...and no dancing on tables". The message was not subtle, so I became aware that my musical talent was something less than minimal.
But thank goodness for the free milk.