My 5 month old is now going to bed at 7:00pm and sleeping till 7:30am. Once or twice a week she will wake up once sometime in the middle of the night which usually requires a diaper change, but otherwise it has been glorious.
We try to keep a really good routine, same nap times every day, same bedtime routine (bath, book, boob, bed), etc. We started crib training at 4 months and that first week was pretty brutal, decided to go with the Ferber method which meant lots of sitting there listening to your baby cry which was hard, but now that we got past the bad part it has been awesome. Probably the hardest part was reading ten-thousand different opinions on how to crib-train your child and deciding which way was best for us.