The Hades rebellion started and was snuffed out merely several months after Sol became stranded, so the GTI must have received some of these fighters or at least parts and the design. This means that the Loki and Zeus projects were already underway for a long time, possibly even before first Shivan sightings (just like Hades). This means that Earth was in possesion of some of these craft, and definitely of lots of parts for them when Lucifer arrived in Sol.
I guess that the Sanctuary was fitted with the best equipement, including Loki and Zeus craft and parts for them. Even if they didn't receive functional fighters of these classes, they definitely had their designs by then - and I think that using ready parts and some resources, Sanctuary could also produce some of these on their own. The Sanctuary was supposed to hide - and what hides better than stealth fighters?