Many got in it before, and many have got in it since, but finally after 19 years it was able to get in itself. What is it?

A newly conceived empty set?

A table of any tables older than 19 years.

/Tomas

Not on the right track yet. What is the 'common' protocol here? When should I give hints?

You could state why the guesses are incorrect then give some hint to the "real" solution or, if any of the guesses fullfulls the parameters of the puzzle but is not the solution you looked for, you can sharpen the parameters of the puzzle to make the guesses invalid.

/Tomas

A broken mirror?

One of those lists of lists or books or records I'd guess. Like Guinness books with a self reference for most records in a book.

Answer: The number ‘8861’ in the year ‘1969’?

Reason: 19 years after 1969 would be the year 1988. The number ‘8861’ could ‘get in’ (‘fit into’) 1988 when turned upside down!

For example:
“Many have got in before”: In the year 1966, ‘9961’ turned upside down would ‘get in’. Similarly, in 1968, ‘8961’ turned upside down would ‘get in’, etc.

“Many have got in after”: In 1988, ‘8861’ turned upside down would ‘get in’, and so on . .

Townsend pretty much hit it on the head. It became the second most selling book in history after 19 years and thus gained an entry in itself. Very nice!

I still don't get it