I started the DF for my DS at 5/5.5 months also to move a NF to a DF. It took almost 2 weeks to stop him from waking up at his normal NF time (first he was waking up later in the night, but gradually moved back to waking at his old NF time). After around 2 weeks of trying, we were able to stop the NW.
DS would wake up when I picked him up to feed, but he would go right back to sleep when I finished. He didn't soil his diaper, so I'm not sure how that will effect things.