I agree that the arvo routine is the first to work on so they go to bed around the same time each day. Usually feed, bath, cuddle/top up feed, bed.
During the day the only routine I have is that she feeds every 3 hours (give or take half an hour) and that I look for tired signs after an hour -hour and a half so I can gauge when to put her to bed. My approach is not to wake them if they are sleeping, so if they sleep after 4pm so be it, but since they usually don't stay up longer than 2 hours before I see tired signs, she is always in bed by 7pm.
I think setting up a routine is easier as they feed less and start on solids.
I have read something that if you write down what your child does you can get an idea of their natural routine and have a starting point of when they sleep best and how often they feed so you have a starting point. I did read one of the books where you put them into a routine but it was too hard and my son fed a lot more than was in the book, plus he wouldn't take a bottle.
I say go with what suits you and makes life easier for you.