Ability to customize date span on Timeline reports

When I view a Timeline report, the Date Span at the top of the page should be able to be customized independent of the dates used for the Milestones or Phase dates in the report. 

Currently, if I use a Milestone time frame and pick Release Phase Start (it's a milestone, but there is no Milestone option in the drop down for this), the Timeline date span will start exactly on the earliest Phase Start date.  This has the effect of cutting off the Milestone dot in the report.

I would like to view at least 6 months before and after the start of a Milestone on a Timeline Roadmap, and I'm sure other users would want a different customization.