Just like everyone else's-I have four and a half years before 50 and this is about 9 years of reading. Add in the fact that I am sure I will get distracted by other books, I am unlikely to finish it by 50 but I will try!
Update- on my 46th birthday, 3 months after this list was written, I have read 10 of these books.
On my 47th birthday, I have read 28 of these books and I believe I am reading another one right now.
On my 48th birthday, I have read 45 of these books.