General rule is 60,000 miles, but they aren't expensive compared to a complete engine ruined by a broken belt. Also as, detdrbuzzard stated, if unknown, change them. An old belt will harden and break.
Honda doesn't list a recommendation for miles or age in the service manual, only the removal/change procedure. 60k is plenty I'd say, and certainly not more than 8 years. Just removing the covers can tell you lots about the condition of them.
The best rule for timing belts or anything else when it doubt.
When in doubt, change them out.
It's inexpensive compared to the cost of what may happen.
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