We can only assume the length of time for the rise of a civilization is roughly comparable, it may be half or twice as much as here, but probably within an order of magnitude or so. Civilizations will be separated not only by space, but by time, as well. Over the lifetime of the galaxy, civilizations may rise and fall, surviving only briefly, sort of like flashbulbs going off at a footbal game. Many of them, but rarely two at the same time AND close together. And we have absolutely no idea how long civilizations last on the average (the last term in the Drake Equation).

And of course, the biggest and least supported assumption of all is that intelligence has a survival value. For all we know, it may be a fatal form of overspecialization that soon leads to the extinction of the species and the biosphere that achieves it.

My intuition (I have no objective or scientific reason to believe this, but I have thought about it a lot :=) ) is that there are at most only a handful of technical civilizations capable of interstellar communication in the Galaxy at any one time.

If civilizations are extremely long lived, older than the normal life spans of species, planets or stars, they can only do so if they are capable of developing interstellar travel, genetic prostheses, machine proxies and descendants, and lots of other things that if they were possible, we probably wouldn't even recognize as artifacts if we ran into them.