White noise machine

We have used a white noise machine for night time sleep ever since our littl girl was born and for naps too once she started napping in her crib.  Now that she is four months old and sleeping through the night I am wondering when a good time would be to wean her off the white noise.  I don't want her to be dependent on it her whole childhood but I like that it drowns out the house noise at night and probably contributes to her good sleeping habits.  Any thoughts or advice?