The New England calendar drives most of this. Startups happen in April and early May once the risk of a hard freeze is past, and a proper startup means charging the system slowly, checking every zone, and resetting the controller for the season. Blowouts need to happen before the first sustained freeze, usually late October into November. Skip one and you're looking at split pipe and cracked backflow assemblies come spring. Between those two dates, the signs you need sprinkler repair are usually visible from the kitchen window: a brown stripe running through green grass, one zone that never comes on, a soggy spot that never dries out, heads that mist instead of throwing a stream, or a water bill that jumped for no reason. Cars and plow blades take out heads along driveways every winter, so a startup is the natural time to catch that.