You don't use the spigot, but rather you tee into the feed to the spigot. If you do this, you should choose one that is the closest to the water meter with a pipe size no less than 3/4". A 1/2" feed will increase your zone count considerably. There are a lot of questions you should/could ask, but you need to do your homework first. A good company will first delineate the sites current and potential hydrozones then design the irrigation system around that. Beyond the critical factors involving design and proper hydrozoning, material quality and a highly flexible (smart) controller are also key factors.