Is there anyway to identify customers who were set up as with COD terms and have been changed to Net21 within the last year?

I am setting up a new Terms Code (Net21N) for new customers who are approved for Net 21 terms so that we can watch them more closely in the first year than customers who have been on Net 21 terms with us for more than 1 year. I have to identify who these new terms people are so I can change their terms code.

I can search for customers based on their start date with Net21 terms but I don't if there is a way to search for customers that may have older start dates, but were changed from COD to Net21 within the last year.

Please let me know if there is an easy way to do this.

Thanks,