I needed a filter that listed only devices that registered today, and cooked up the attached filter (based largely on the "Agents installed in the last N days" report. This filter can easily be modified to show devices that registered 2 days ago, 3 days ago, 5 or less days ago, etc. Just download the attached zup file, extract the contents, and import the filter and start using it in your targets.
If you need to make such changes, edit the following line in the SQL to suit your needs.
and datediff( dd, rus.[CreatedDate], getdate() ) < '1'
Simply change the < '1' part as needed. For example, The above will return devices that registered today. <= '5' would return devices that registered anytime between today and 5 days ago.
I've only tried this in 7.5, but presume it would work in 7.1.
Hope you find it useful,
-Chris