I am having trouble finding the exact mileage for the T-belt. Sometimes a car maker will say 'as needed', like Lexus does with its big sedan. I would definitely do it by 90k. The basic job is about 4.5 hours of labor and the belt which is comes to about $400-500 depending on labor cost in your area. The best way is to also do the water pump, the seals, the ilder and tensioner which will generally run about $1100. If you intend to drive the car for 200k, the second option will actually save you money, because to do these as they wear out will cost much more in the long run and they will fail before the next belt at 180k.