How fast can i get data from a USB device?

I realize that this depends on a lot of factors, but if anyone has a ballpark idea, it would be helpful.  I'm considering building a peripheral device and interfacing it with a computer via usb(which will admittedly take a bunch of research on its own), but i am curious how quickly data can get into a program from a USB port.  Like, can it go as low as nanoseconds?  Or is it as slow as milliseconds?

And i don't mean the speed of the data along the cable, i can just look up the speeds of the latest USB standard.  I mean, how long it takes a program that executes some "get data from usb port" function to actually retrieve that data and be available for use in the program.