When should I transition from a swaddle to a sleep sack?

Specialist-subreddit consensus (notably r/sleeptrain and r/newborns threads in the data) is to stop swaddling at the first sign of rolling, typically 8–12 weeks. Arms-up zip swaddles like the Love to Dream Swaddle UP are commonly used as a bridge because they allow self-soothing without the Velcro escape problem parents report with traditional swaddles.