One of the things that Better Dead Than Zed does much better than the original All Things Zombie is to give me an emotional connection to the Star and his group of companions; partly because it starts on Day One of the outbreak, not two years afterwards, and partly because you are encouraged to play Day One as if it were actually happening to you.
As background for the 28 Months Later campaign, I wanted to understand better what would still be available to survivors over time once civilisation had collapsed. (Wargaming is very educational, and takes you off in all sorts of strange research directions.)
I originally planned to work this out myself, but then thought: It’s so obvious a topic that someone else must already have done it. And indeed they have; you can find timelines in increasing levels of detail here, here, and here. Since civilisation in ATZ collapses over roughly a one month period, you may want to adjust the timelines for the first year or so to reflect that.