You can Sort your collection by the date purchased. To do this, use the menu Collection/Sort By.../Date Purchased (ascending or descending) OR you can right click in the collection list and find the sort there. You can have the purchase date show by right clicking on the collection list and select View Columns and pick what you want. Seeing the purchase date will make the next step easier.

Then Flag the titles you want in the report by pressing the space bar when that title is selected. Each press will advance the cursor down the list, which makes selecting a group simpler.  When running the report, select "Flagged entries only" on the lower right side of the window that opens. When you are finished, you can clear the flags by Shift+Ctl+U or Collection/Flags\Unflag All.

If this is something you think you would want to do all the time, you might want to create tags for each month and year. Then you can filter on the tags (ie: Feb and 2008) and all profiles you tag for Feb and 2008 would be the only ones showing. Then select "as filtered/sorted in collection listing" to print only those profiles.

Hope that helps. If you have any more questions, ask away. Welcome to the asylum.