Terrestrially, 520 years is more like from the Bronze Age to the Classical Era, which was part of the Iron Age. From the Bronze Age to interplanetary space flight is more like 3500 years.
I think it's more likely that CoE will start in the Iron Age, and possibly fairly well into the Iron Age. That's because blacksmiths will be common, and because bog iron (swamp iron) was mentioned in a dev post. That would put the terrestrial equivalent technological era at start somewhere between 1000 B.C.E at the earliest to around 1500 C.E. at the latest. The costuming and general item pictures seem to be from around 1000 C.E. and later, terrestrial equivalent. Certainly the quality of the items shown as available to commoners are far more advanced than a 1000 B.C.E. terrestrial equivalent.
Who can say how rapidly science and technology will advance, compared to RL earth? I don't see how it can advance as fast as RL earth did, if the game turns into a PVP gank-fest, which seems to be the hope and expectation of many prospective players.