One of the default views in the iTunes sidebar is Recently Added. But you can’t change the scope of this view. The oldest music I see in Recently added on my iMac is four months old (1/22/16), but a bit older on my MacBook (1/2/16). I had added music on my iMac on 1/19, 1/18, 1/14, and several other dates closer that 1/2/16, so it’s odd that this should be different on two computers.
Another problem with this Recently Added view is that you can only view the music by album, in grid view. You may want to view your recently added music differently. If you want more control, make a Recently Added smart playlist.
Choose File > New > Smart Playlist, or press Command-Opton-N, and set the following condition:
I’ve set the condition for 6 months, but you can change it to any number of days, weeks, or months.
Click OK, and you’ll be able to view this playlist in the sidebar. However, it won’t be at the top like the built-in Recently Added view. But you’ll be able to choose how you want to view the contents of this playlist: by album, artist, song, genre, etc.