Developing Trend Analysis

I am wondering if someone here with more experience might be able to help a newbie like myself out. I am hoping to create a trend analysis using a line chart to show our company's customer receivables balance aged over 60 days. Right now it is fairly easy to get the report set up for as of today, but what I want is to be able to have these balances pulled into the line chart for prior points in time to see the trend of how we are performing in lowering the balance over time. It seems like I would need to create a date table to link to the main invoice table, but how else would this need to be approached? I have a field in the invoice table called DocBalance that hosts the current balance on the invoice, would I be able to just use this field to backtrack across dates to get the DocBalance as of a specific date?

Hopefully this makes sense and thanks for any help.