we didn't have much of a routine for the first few weeks as Freddie seemed to change his mind every day about when he was tired enough for bed and just went by Freddie's cues as to when he was tired and wanted to sleep, it wasn't until he was about 10 weeks that this seemed to happen at the same time. we tried the whole bath bed thing but the bath didn't help make him sleepy, in fact he stayed awake longer and really screamed cos it made him overtired. i bath him in the mornings now, it means we can have a play and not worry about having to get him to sleep afterwards. so all we do now is 6.30 sleepsuit on and last change. sit down, read a story or look at a picture book and snuggle, feed and then bed. all of this we do upstairs in low lighting. I think it also helped having a more firm routine in the day as well, not just at bedtime.
really hope Isla lets you get some good sleep in soon