What I would suggest is creating calculated fields for these percentages (Before %, After %, and On Time%).
Once these are created, you can drag "Measure Names" to your columns to separate them out.
Please see attached workbook for example.
MeasureNamesColumns.twbx 1.2 MB
Thanks for your reply with an attachment. I'm using version 9.2 and hence, unable to use your example.
I've updated in 9.1. Please find attached.
This is using Superstore data, so in your data, you'll probably need to put a little more logic in the "% of Total Calculations" (Something like, "If [OnTime] = "Before" then [Forecast] else null end" for each time period, and then doing a Table Calc of Percent of Total on those.
MeasureVallueRows.twbx 1.2 MB