send actions on user input only

This is just a suggestion pertaining the target/action mechanism, not KVO and delegates: when you change the date programmatically, do not invoke the target/action pair. That's more in line with programmatic changes to AppKit components like NSTextField.

In my case, this does not result in fetching the initial data twice, but by default it would if you populate the view with something and then have data for the same range requested again.