When do I really need to replace 1998 Sienna timing belt?

Owners manual says change timing belt at 90,000 miles only if van is used for low-speed deliveries. Otherwise, there's no mention of timing belt (maintenance chart ends at 135,000 miles). I drive mine normally and have 130,000 miles. Have also seen recommendation to have belt inspected at 120,000 miles, but dealer is likely to be cautious and recommend replacement regardless of what inspection shows. Wikipedia says "unofficially, don't worry until 200,000 miles." Any mechanics or Toyota reps out there have some honest advice -- do I need to worry about the timing belt yet? Thanks.