Maybe we're lucky, but by 3 weeks, we had the sleep thing down.
Yeah, we really can't complain. First few weeks were rough, but he settled into a good routine pretty quickly - other than the one week where he was eating approximately every 90 minutes.
We still have him sleep in bed with us (big no-no, I know), and, other than when he's teething or sick, he only wakes up to eat once or twice during the night. Once he's weened (should be pretty soon), we'll start working on getting him back in his crib most or all of the night.
He does have a nasty habit of sleeping sideways across the bed, and I usually get the foot/diaper end for some odd reason. Go figure.