Here's a Timeline of Innovations and Achievements to Help You Decide
- 1994 Desktop Computers
- 1950 Television becomes popular
- 1927 First commercial airline
- 1920 Ideas of black holes, space-time, and nuclear energy proposed
- 1908 Automobile becomes popular
- 1901 Radio begins to replace telegraph as long-distance communication of choice
- 1883 Sterile techiques developed
- 1881 Vaccines become popular
- 1868 Transcontinental railroad
- 1858 Transatlantic ocean floor telegraph cable enters operation
- 1824 Telegraph enters common use for long-distance communication
- 1804 First steam railroad in Europe
- 1787 First commercial steam boat services
- 1763 Bayes Theorem (statistics) published
- 1751 First battery
- 1745 First capacitor
- 1670 First lecture by Newton on optics
- 1621 Asphalt used for granaries and sewage systems
- 1500 Printing press enters common use
- 1300 Dry magnetic compasses enter common use in Europe
- 1280 Building-size clocks enter common use
- 1086 Fulling mills (automatic manufacturing of wool using wind/waterwheel power)
- 586 Ship mills (boats doing milling - Constantinople)
- 500 Hospitals (Constantinople)
- 490 Theory of Impetus (similar to Laws of Motion)
- 100 BC to 205 BC Antithykera Mechanism (computers)
- 280 BC Automatic Servant of Philon (robotics; Byzantium)
- 800 BC Alphabet introduced to the Greeks
- 2,000 BC Oldest pottery (Brazil)
- 4,000 BC Oldest dyed cloth (Peru)
- 5,000 BC Copper mining (North America)
- 7,000 to 9,000 BC Gobekli Tepe (carved stone, farming)
- 40,000 BC Earliest cave paintings (bull)
- 500,000 BC hundreds of flint axes found (Boxgrove)
- 700,000 BC flint tools found (Pakefield)
- 1.2 Million BC 50 handprints found (Happisburgh, England)
Based on the list above, I think there's not a time where anyone is going to be blown away by technology. I think a guy from Boxgrove 500,000 BC is going to recognize that a steel axe is just a much stronger version of what he's familiar with; and that houses are just better versions of the what he possessed. A guy from Byzantium 280 BC is going to see someone operating a computer and get an idea of what's going on, even if he/she will need instruction to use it.
On the other hand, you have cargo cults (1940s) that were pretty impressed by airflight. Certain things (airflight, spaceflight) might just be much more impressive than others.
I think it depends on the person.