When he turned the key to detonate the Swan the FST was created and he was in fact shot there.
Evidence to this is his interactions with Eloise. Notice how she tries to control what he does and doesn't, and how she has an idea of what's going on. You can not marry Penny, don't change things, WHH. (but not really because this isn't the real world and Ellie knows this - shes worried about people moving on without her [ie Daniel])
In the FST (post 815 not crashing), she also tries to control what Desmond does and doesn't. We see this in the party scenes where she reprimands Desmond for ignoring her.
So it seems we saw the FST for the first time in Flashes Before Your Eyes.