Pre-space age yinrih history is somewhat messy right now, but current lore has them achieving spaceflight 5 millennia after achieving sapience. Given their much longer lifespans (~723 Earth years) this would be like humans going from crudely knapped flint hand axes to orbital flight in 500 years. So they're in space before humans leave Africa. My (admittedly weak) justification for this is that they start the game with writing unlocked, there's no ice age to impede the invention of agriculture, and religious zeal is one powerful motivator.

I don't have any specific dates for hot air balloons, although it is the first thing they mess around with. I do have them playing with Jules-Verne-esque manned projectiles around the year 1406 AK (about 2000 Earth years after the first evidence of written language). This begins a period marked by high casualty rates among research monks and their lay assistants. These brave souls are known as the Cannonized [sic] Martyrs.