*When* you're ready for indoor flight, the night vapor requires a room about 20x20' to fly well. I can barely fly a figure 8 pattern in my 20x20x8' finished garage without going into high alpha -- any smaller and you'll have to fly it like a helicopter to change directions.
PZ lists the minium size for the mini-vapor at 15x15' - I can't confirm this, but it is lighter and has a MUCH slower prop, so it's possible. there are a few living-room-flyers on the market, but many haven't been kept up to date and can be more expensive that medium sized outdoor flyers. If you can go to a small gym size or better, the indoor flyer market picks up quite a few nice inexpensive options.