The best time to replace a 2004 Chevy Venture timing chain is when it becomes weak or broken. It is not something that needs replaced routinely.
It has a timing chain and gears. NO timing belt.
Chain
Timing belt
It must be a timing chain because Gates ( they make timing belts etc. ) does not list a timing belt for the 2004 Chevy Cavalier
it has a chain and does not normally need to be replaced
Wath timing 2.2 malibu 2004
Pushrod engines have a chain. Overhead cam engines have a belt.
I contacted the Chevy Dealer and he informed me that the Chevy astro van has a timing "chain", not a timing belt and requires no maintanence action for this item.
Your question really makes no sense. Normally a timing chain will last the life of the engine as replaced when the engine is rebuilt.
Timing chain.
2004 Nissan Maxima has a timing chain.