The timing belt service interval for an 06 Sienna (my wife’s) is 7yr/90k miles, whichever comes first. Your van is 18k overdue. The 3.3 6 cyl is an interference engine, a timing belt failure would be catastrophic and the cost would be thousands not hundreds. Is your friend willing to pay for a new engine if the belt breaks?
I would have the belt, tensioner, waterpump, and any other related parts replaced ASAP.
Ed B.