The official Roomba owner's guide doesn't give a time estimate. However, some customers suggest that it takes a Roomba between 40 and 60 minutes to make its way back to the Home Base.
Does Roomba learn your floor plan?
iRobot says the device can remember up to 10 floorplans, meaning you can “kidnap” it, take it to a new place, and it will learn that one, too. (It will also work with Alexa and the Google Assistant, so you should be able to shout at an Echo Dot for the Roomba to clean a specific room you've just sullied.)
Why does Roomba take so long to go home?
If your Roomba is taking an abnormally long time to head home after cleaning, it may be having trouble navigating the environment. It must have a clear path to the charging station, which should be up against a wall and away from stairs.
How long does it take for Roomba to map your house?
Usually, two to three mapping runs will generate a full and complete home map. If you want your bot to earn its keep by vacuuming while learning, it may take up to five outings before a full map is ready; this depends a bit on the size and layout of your home.