When to change timing chain on my 2002?

When should I get my timing chain replaced on my 2002 Toyota Tacoma

 

When it starts to slap against the timing chain cover?

Supposedly these are "lifetime" chain. I don't buy it but I can attest to the chain developing no stretch after 200k miles and being run low on oil long enough that the timing cover egged out where the oil pump rides.

I replaced the chain anyway but I'm more worried with the new one because I used an aftermarket chain and not OEM

 

When you get to 250k, start thinking about it. Most likely won't need it, though.

 

Toyota chains are pretty stout... never seen a 2.7 chain need to be replaced. My 06 corolla with over 800k on it is still on the original chain. Typically the chains will last the life of the engine unless oil changes are neglected