That's my best assessment of the information I found. Note that on the census records you already have Nora is listed as son/male. You had this correct on your tree. On 1920 (which was taken in January 1920 (see top of page), Nora was listed as 1 2/12 years old. That would make his birth in November 1918.
I searched the Kentucky births database here.http://search.ancestry.com/search/db.aspx?dbid=8788
I used last name Henderson and mother's last name Stamper. I turned up only two births. William R. in 1922 and John W. 20 November 1918. I have to assume that Nora was some kind of a nickname.
If you get an obit for the John W. Henderson I mentioned in Tennessee, and/or for William R., that may resolve this.
By the way, the KY births database is a great resource. You can find whole families, or you can determine the mother's maiden name -- as in this case. Don't pass up an opportunity to check all your KY people born after 1911 in this database.