The query "how long since 9" is ambiguous. However, some relevant interpretations and their answers based on recent web data are:

• If the question refers to how long since September 9 of last year (September 9, 2024) until today (August 29, 2025), the answer is approximately 11 months and 20 days, or 354 days.

• If the question refers to how long since the year 9 AD, it has been about 2014 years and 6 months, or 735,782 days.

• If the question refers to how long until next September 9 (2025), there are about 12 days left.

If more clarification is given on what specifically "9" refers to, a more precise answer can be provided.