As long as it isn't
Ankha meets little green man (alien) and makes Egyptian pyramid UFOS Egyptian-Alien Collaboration Extraterrestrial technology left over on the planet where cavemen find out about the technology and try to reverse engineer it, then the answer is, a very long time.
Basically, it is very hard to get into space, much less build bases on planet.
Assuming that your planet is Earth-like and has Earth-like gravity, then you are in for a very bad time.
It took us about 10,000 years, from the first civilization (Babylonia and whatnot) to become smart chad rocket engineers who can make powerful rockets like the Saturn V (The most powerful rocket engine ever built, not counting the SLS) which launched man to the Moon, and the Titan-Centaur-something rocket, which launched the farthest man-made objects, the Voyager probes into space, about nearly 17 billion miles away from Earth, and has exited the heliosphere already.
Even then, it is a pain in the a** to build a decent rocket even today, as most fuels used today in rockets are mostly Liquid Hydrogen or kerosene (Don't get me started on hydrazine or other complex fuels, that will take a ton of explaining).
Liquid hydrogen is of course, fiendishly difficult to create, store and use. Most H2 manufacturing uses steam-natural gas reforming
bombarding natural gas with steam or fiendishly inefficient electrolysis, if you are a green hydrogen enthusiast. Furthermore, hydrogen atoms are so small they can escape through even our most tightest containment cells, and hydrogen is known to damage metals by hydrogen embrittlement. Also, although most gases cool down upon decompression, hydrogen heats up when expanded, unless you cooled it down to extremely low temperatures, due to some long-range molecular forces blah blah and other jumbo that will take a lot of time to explain. You can check out this ChemStack answer, if you want to know the reason. But, in short terms. Liquid hydrogen is about as difficult to maintain, as trying to keep a Siberian tiger and an mountain gorilla in the same room from attack each other (note: It will not work).
You run into some luck with kerosene, tho. Kerosene was used in the Saturn V for the first launch stage (the later stages used LH2-LOX), to blast it into space. Using Kerolox (A mix of kerosene and liquid oxygen), they managed to get into orbit.
However you again run into another problem: Kerosene tends to freeze in space, clogging up motors and whatnot. So again, you are back to the drawing board.
And don't get me into the problem of making a oxidizer. Liquid oxygen is a bit more merciful than liquid hydrogen in manufacturing, but again, LOX is really corrosive. Pure oxygen is about as safe as standing near to a atomic bomb initiated (Don't try it). In its pure form, oxygen is essentially the smaller bro of fluorine, it is less reactive, but not by much, which makes oxygen a voracious oxidizer. It has been known to attack xenon and platinum, reacts with hydrogen so violently it's like watching a mini-MOAB/FOAB exploding, and other catastrophic reactions. So, liquid oxygen is dangerous to handle, in general.
All this doesn't mean your space-faring civilization is going to be impossible tho. We have managed to store LOX and LH2 safely somehow, and we have actually sent men to the moon properly. However, since the problem of landing rockets on each planet is still a fiendishly difficult task to accomplish, it will take a very long time.
My final reliable answer: 9000+ years or so.