Check this out, it's a really good article about the forth trimester:
It makes so much sense! Personally I carried my babies until they are in deep sleep then put them down. if they woke up I'd pick them up and carry again. my girl is 9 months old now and only recently she is ok when i put her down. During her earlier months I would carry her through her naps.
With swaddling my son was swaddled for 8 weeks, he hated it. My girl only 2 weeks as it was too hot plus she wasn't jerky.