I don't know of a timing chain service interval for that motor. Most vehicles with overhead camshafts do not have service intervals. These motors have adjusters that take up timing chain slack due to stretching To replace these chains, the whole front of the motor needs to be disassembled. The chains are changed when the motor is being replaced or you could possibly change them if you have the cylinder heads removed, (for whatever reason) but I would not start to worry until you have over 200,000 miles. This is assuming you are following a good maintenance routine.