Version 7 will be released soon.
Read the v7 docs
dateAlignment
Determines the first visible day of a custom view.
String
When a Custom View is being used, and you’d like to guarantee that the view begins at a certain interval, like the start-of-week or start-of-month, specify a value like "week" or "month".
If not specified, a reasonable default will be generated based on the view’s duration.
If a view’s range is explicity defined with visibleRange, dateAlignment will be ignored.