Really, it's all tied to when the grid goes out.
Once this happens, and it is obvious it isn't going to be up soon (a very key point, as until then, there is hope)....then it will be a matter of days before we see nearly complete anarchy occur.
This will be the most dangerous time of the whole deal. No doubt, governments will roll into major cities with military force, but they can't cover it all (and eventually, soldiers will realize they are pretty much on their own), and non-major urban centers will be completely lawless (looting, murder, rape, you name it, as people fight for few resources). Initially, I think we'll see a large number of people dying off during this time through violent means. Within a couple weeks though, starvation will claim even more, while others are still dying due to the violence. Within months, you'll see many more die off due to disease and lack of sanitation.
During the first couple weeks, I think those of us in rural areas are basically safe (maybe a lone maruader, or small band, but few and far between). After that though, when food is running out in the cities, folks will use what gas they have and check the surrounding areas. For us, this will be our dangerous time (2 weeks after, to about 6 months after). After 6 months though, nobody is really going to have the fuel or much in the way of working tech, to be very mobile. Sure, there will be some smart bands who have looted, etc. and have some resources, but even these guys are going to pick targets giving them the best bang for the buck...like warehouses, large stores, etc.
This is why the key to safety is location. If you are away from large urban centers, simply put, the lack of working tech is going to keep you geographically isolated to a certain degree.
Not saying you can't survive in a city. You can, if you lay low (or join a gang). Otherwise though, you're just going to be one of the countless victims. Staying hidden will be the key, but also hamper any attempts to gather resources. Joining one of the gangs may be a short-term option (and if you lost your morals), but even then, violence is likely your biggest threat (and competition within and with other gangs and survivors).
I'm not naive enough to think we won't have to look around and loot some (abandoned) places. Things like hay, feed, canned goods, medicine, fuel, etc., we'll probably need to loot. But, we will steer clear of any such target that is contested, as we're not going to risk our lives for it. Better yet, this would only be needed if the SHTF prior to having all preps in place, as the eventual plan is to be able to switch into being completely self-sufficient.