@Ranjeetv Not the best and most convenient way to do it, but you will need to start the interval on or before one of the days you can water. Make sure to start it before the runtime.
So, for example, if you needed to run your system every 2 Wednesdays and you wanted to start it at 2am, on Tuesday night you would update your schedule to run every two weeks, starting at 2am. Again, not ideal, but will work in the short term.
We will be adding the ability to start an interval on any given day in version 1.4.0.