You can set your axis value to show a certain timeframe before your start date. Set the minimum value to

DATEADD(DateInterval.Month, -1, Parameters!StartDate.Value)

or however far back you need to go....

Well, the technicalities depend on what version of SSRS you're using but if you know your way around ...

Just go into your report parameters.

Create a parameter named LabelBuffer

Set...

Great article - thanks! 😉