Several years ago I waited until the first hot day of summer to turn on my AC. This is how I found out about one of the busiest times for repairmen and had to sweat for two weeks. Now I do a test run a couple of weeks before it heats up. Same goes for the furnace at the end of Autumn.
Also it’s become very expensive compared to the new stuff for this reason. Like over 10x more expensive per pound.