i swaddled my LO until she was about 27/28 weeks. i didn't force weaning the swaddle because she dropped it when she was ready so don't worry about it. however, if she's rolling, we may need to find an alternative to having her arms pinned.
anyway, those jolts happen at 10 and 20 minute mark. sometimes though, either of those jolts will wake her up completely and she'll have to start all over - new jolts at 10 and 20 minutes. if she's not rolling, the only thing i know of is to swaddle so her arms don't fly up and to stay by her bed and shush if it wakes her up. she'll outgrow them.
melissa