We transitioned our little one to her own crib around 10 weeks. She slept much more soundly once we placed her in her own crib, rather than the portable bassinet we had at our bedside. I'm assuming this is due to the crib mattress. She's almost 9 months old now, and sleeps in 8 hour stretches. The mattress is clearly marked so you know which size to use for the crib and a toddle bed. So far, so good.