6 weeks was about the time I introduced a bedtime routine.
Maia didn't like a bath back then so we just used to have a massage in her bedroom with a lullaby cd playing in the background, get her ready for bed then feed, wind and down in her cot in our room.
The time we did this always varied depending on when she last had a nap, but usually she would be in bed anytime between 6:30pm and 7:30pm leaving me and hubby to make our evening meal and sit and relax. She could go roughly 1 hour 30 mins to 2 hours between naps so I always knew how long I had for our routine before she would start to get tired and cranky. If she needed a feed close to our bedtime routine I would feed her but only give her half of the usual time on the breast then take her off and finish the feed as part of our routine. Now she generally feeds as part of our routine no matter when her last feed was cause she knows its bedtime and knows she needs to fill up in order to sleep through.
Thats the only routine we have, I know she will always want to nap in the morning then again at lunch and then in the afternoon but I just let her take the lead on when she wants to sleep and eat.