I downloaded the excel spreadsheet, I think it's a very cool resource, and quite managable (but I have MS Excel).
DVD_ReleaseDate is in column M. I sorted it by this field, and Return Of Boogeyman (Boogeyman 3) was the first R1 title, from 2/1/1997

. It also says Criterion's This Is Spinal Tap was released on 7/14/1998.
There are almost 55,000 titles with 14 information fields, or 766,290 pieces of information, so you are definately going to want some piece of software to manipulate the information. I would avoid the HTML version. Do you have any spreadsheet or database program? Any one of these should be able to read the Comma Separated Values (CSV) file.