When should I start building up fail stacks with Accessories? I'm starting to go above +7 weapon &amp; +5 armor.

So far, my weapon is at +8 with 2 fail stacks.  

I think I'm starting to understand the concept of fail stacking, and I really should be trying to build up "X" amount of stacks via cheap Accessories before attempting a weapon / armor upgrade.

My question is whether I should be trying to do this from the get go when my upgrade levels are currently low.