I'm not suggesting that they were definitely released in 1911 but I think it's something to look into the article does say appears on not appeared. Did the 1910 date come from the teams that some of the players played on?
It wasn't like they took the pictures and a month later they were in the cigarette packs. A lot of work had to be done before they were distributed in the packs.
Earlier this year I posted this clip from March 14 1910 and they're just talking about taking the pictures of the Carolina players so the pictures are most likely from 1910 but how long before they made it into the packs? They were right in the middle of printing the T206's at the time they were talking about the T210's.
Charlotte_Daily_Observer_Mon__Mar_14__1910_.jpg