NoI say, no. It's not cheating. It's practicing. It is a stepping stone on your way to bigger and better echolocation accomplishments. To an extent, yes, you will be navigating somewhat by memory. Having a general understanding of where things are and what to be cautious of in advance can detract from the sense of echolocation and the effectiveness of your training.
Careful though, if you simply walk around your house completely by memory, but making clicking noises, that still may not be effective learning. It is critical that you exercise your ears and really focus on the sounds you hear and start getting more comfortable with the subtleties you'll notice at every doorway and every corner.
Take it to the next levelOnce you get comfortable echolocating around your home, or you have become "calibrated" to your surroundings, have a family member or roommate change the location or orientation of some of the furniture. This will help you avoid becoming complacent and will require that you are always alert and paying attention to the minute details of echolocation.
Another thing to try is opening a window or door and seeing how that effects your calibration.