When did we do it for the first time? I have no idea.
At some point, however, it was the winter and we wanted to use our fireplace. I generally found it hard to time a fire though. The (I believe at the time it was singular) kid went to bed relatively early. If I started the fire early, then Hillary or I would be cooking while it was going.
Then it would die down significantly before we had things cleaned up and were ready to relax for the evening.
So the solution was to have dinner, our nightly together time, in front of the fireplace. But then we're faced with the idea of having a picnic on a carpet with a sub two year old. This seems like a poor idea.
I remember my solution being met with skepticism. I brought down an old sheet that was getting a bit frayed and literally didn't fit any beds we owned at that time.
I laid it out, weathered the looks from Hillary and we had a picnic in our living room. It was fun, almost no mess made it off the blanket, and no cups full of milk were kicked over that day. It became a thing we'd do at least a couple of times every winter.
This winter, it seems that tacos are our fire picnic food of choice. Twice in the fall I suggested picnics on nights we had tacos. So sure enough, when tacos came up again, the kids just enthusiastically reminded me that we always have a fire when we have tacos.
I think I like that extra requirement. The fire picnic is a bit less general now. Making it more specific makes it feel just a bit more like a thing that I and the kids do and less of a thing that we did with Hillary.
The kids loved the living room picnic and we'd eventually do them throughout the year if there was a special occasion. I'm pretty sure the first time I made salad rolls was a living room picnic as well.