R&R time to change timing chain GM 4.3?

How much time dose it take to change the chain on 2001 4.3 S-10 Blazer?

Any tips to make the job easier

Forget time. Most important is you know what are doing. If you have a book that describes the exact procedure, and you have a deal of mechanical experience, then follow the instructions.
You should change the water pump as well while you are at it.
Aside from any of that, I always lay out parts and bolts and nuts as I remove them and leave them that way, aside from whatever else I am doing, so that when I put them back I just have to reverse what I took apart.

It is odd that this job is popping up as it is not a maintiance item, care to explain what is going on?

With the chain job your toughest challenge will be getting the harmonic balancer off and on without damage and assembling the timing chain cover so as you do not have a oil leak at the point where the pan meets the cover.