How long would you shake your baby (< 10months) in the sarong/ yao-lan, to encourage her to sleep?

I wouldn't use a yaolan as it is not safe for babies. It also makes the baby reliant on it. Without it, the baby has a harder time falling asleep. Do try cradling your baby and using a soft, rocking motion instead. Babies feel calmer when they are cuddled close to their parent's chest. My baby hates being carried in the cradle position normally, but when she's sleepy, cradling her works wonders. If you really need an answer specific to your question, then I would say until the baby falls asleep. There are automatic yaolans which do the shaking for you. http://www.healthxchange.com.sg/News/Pages/Sleep-Right-Sleep-Tight.aspx