I have had many discussion with many moms who had crying babies at the age of 6 weeks. This is what worked for both of my children, mostly based on Dr. Weissbluth's book, "Healthy Sleep Habits, Happy Child."
6:30/7 pm: Bedtime
10 pm: Nurse
1 am: Nurse
4 am: Nurse
6:30/7 am: Awake and nurse
When baby shows drowsy signs, it is naptime - never more than 2 hours of wakefulness.
10 am: Nurse, play (could be less than a few minutes for a newborn,) nap
1 pm: Nurse. play, nap
4 pm: Nurse, play, nap
This schedule worked for us, and I made sure Baby got a full feeding (until both sides emptied.) And of course, if Baby is underweight or hungrier with growth spurts, you should feed more often. Please see my entry on nursing in Sleeping Babies, Healthy Babies Part II. Also, if baby is sleeping through, do not wake her up. Let sleeping babies sleep.
As baby grows older, the third nap disappears, then the first one, followed by the second one. As baby starts solid food at 6 months, there is nursing, play, eating and then nap. The nursing disappears after 1-2 yrs. (I did 18 months and 1 yr.) Granted, you have to take these hours with a grain of salt since babies are not clocks, but it is within a 30-45 minutes window. I let my second baby cry a bit before naps and she quickly learned to fall asleep on her own. I gave her a small piggy washable stuffed toy every night earlier on in her pack-n-play, and that was her security for a while.
This schedule allows the child to maintain this sleep pattern throughout their toddler years as the nursings are dropped and solid food is served at regular meal times of 7:30/8 am, 11/12 noon and 5/5:30 pm. With an earlier dinner, children can sleep by 7/7:30 for a full 12 hour night. Early years of JK, SK, primary grades are transitional and emotional. A full night's sleep and healthy eating on times are crucial.
I highly recommend this book! It saved our sleep and thus, every every other part of our lives. If any of you have babies or are pregnant, please read if you haven't already!