I have a date field.  Lets call it z_udf_date.  I want to pull that date regardless if it is populated or empty from the start of the current month to the current date with the ability to rollover next month so it starts over on Feb 1.  I also want to pull that field if it is empty prior to the current month.  Does anyone have any ideas?  Thank you ahead of time.

So far I have {invoice_head.z_udf_date_1}=MonthToDate which bring up all dates starting Jan 1 to current.  I now need to add all previous months prior to Jan 1 if that field is empty.  Do you know how I incorporate that into my current formula?  Thanks!