The answer to 'best time for irrigation installation' is that the optimal time to install a new irrigation system is typically in the spring or fall, when temperatures are mild and plants are not under stress. This allows the system to be properly installed and tested before the peak watering season.
Installing an irrigation system in the spring allows it to be ready for the summer months when watering needs are highest. Fall installation is also a good option, as it gives the system time to be tested and adjusted before winter, and the ground is still soft enough for digging. Avoid installing during the hottest summer months or the coldest winter months, as the ground may be too hard or dry to properly install the system.