If it is actually a timing chain and not a belt; then possibly never. Timing chains last many hundreds of thousands of Km's (Miles). They should have an automatic tensioner and slippers that will need to be replaced at certain intervals. If you have your original service book it will tell you when to change the timing chain/belt.
Update: on the 2011-13 year models there is a recall for timing chains, for a free fix. Due to a faulty component. Book your vehicle in to a dealership and ask them to check it for all recall campaigns. If any are required they should be fixed free by a dealer.