In my mind, survival mode starts when you're into difficulties and you can't see an end to it.

This could go from being at home in deep winter when the power goes out to being on the road in a remote area when your transportation gets disabled.

Lacking a little LED that flashes when a survival situation starts, I've done as you have and preplanned. I carry and/or store what I think I may need in situations where the trappings of civilization are just not available.