I would love to know if the 5 Ss are mainly for newborns or if you can start with an older baby (12 weeks)

The 5 S’s will still be beneficial if you begin swaddling your son as they work well past 3 months. Also, swaddling correctly is the cornerstone of good calming and sleep. Dr. Karp recommends swaddling at least until 4 months of age, and many babies need it until 5, 6, 7 months of age. If your son is getting out of the swaddle, the blanket may be too small or he is incorrectly wrapped. The Perfect Swaddling Solution is a great swaddle blanket as it is a large, thin blanket perfect for getting a snug swaddle and can be found on our website.