@richgran, as @ghctim mentioned, this will be a feature of Flex Schedules, which will change the frequency of watering to match the water requirements for each zone. In addition to rain events, we'll also keep track of manual runs as they also impact how much water your lawn gets and needs.
This is not a feature that will be included in 2.0. When editing Fixed Schedules (aka Watering Times in the 1.X app), we'll prepare a watering time and frequency of watering. Any changes to our recommendations have to be overwritten by the user. Nevertheless, the first watering day can be customized. To change the start date of the watering time, please see #5 in this support article.
Hope this helps