I use start before and start after watering for two controllers. I use Flex Monthly and have one grass schedule and one flowers schedule for each controller. The Rachio controller doesn’t modify watering time to fit within a time period so if you run both on the same day one unit needs to be set to finish by 4AM and set the other too start after 4AM. Depending on how many zones need to run the one may start before 10PM and the other may end after 10AM. My units don’t have any overlapping turf zones so it doesn’t matter if the front yard waters one day and the back yard another day. I would keep all overlapping turf zones on a single schedule and not do flex daily as the overlapping area will be watered unevenly than the areas that don’t overlap with the next zone. Also for simplicity make sure that you have separate common wires for the two controllers. If you share a common you have to add isolators which there is diagrams that can be found in the forum.
