I think the thing to keep in mind as well, is there will always be set backs but it is important that to stick with the routine as much as possible. My DS has just cut 2 teeth and had a really hard time with it and was quite unwell, so he needed extra help getting to sleep- and some night ended up in bed with us- BUT now that he is better we are back in routine, it is taking a bit extra to get him off, and some nights I am having to sit in his room for a bit until he is almost asleep before I sneak out, but slowly I am shortening the amount of time I stay, so now it is just a couple of minutes and I sneak out.