I imagine each location is different, but where I live the ONLY thing the county cared about was the backflow device. They could care less about the irrigation system. Where I live they didn't require any plans, the only requirement was that the backflow device be installed properly.
I got my permit, installed by backflow device, ran a section of mainline (capped it), and got it inspected weeks before i even began to install my system.
I would call the county/city and ask specifically what they require for plans.