Question: When did ernie first appear on my three sons?
Disambiguated questions and answers: question: In what episode number did ernie first appear on my three sons?
On what date did ernie first appear on my three sons?
In what season did ernie first appear on my three sons?
answer: 118
October 31, 1963
Season 4
question: When did Ernie first appear on my three sons (episode number)?
When did Ernie first appear on my three sons (date)?
When did Ernie first appear on my three sons (season)?
answer: 118
November 7, 1963
1963
Season 4
Natural Questions answer: 1963 (from the Wikipedia article "My Three Sons")