I visited Paris in November 2017 and didn't have to wait at all to see the Mona Lisa. The room had a good number of people in it, but wasn't crowded. My advice:

I visited Paris in November 2017 and didn't have to wait at all to see the Mona Lisa. The room had a good number of people in it, but wasn't crowded. My advice: If possible, take your trips in the late fall!