Sasha,

I think their first sleep cycle is about 45min give or take! DS had dramas with resettling during the day also! He slept through from 3 weeks (a good 10 hours a night) but only cat napped during the day (30 minutes if that)! And yes persistance is the key as it's taken till now (3 months) to get him to the stage where he resettles by himself, i used similar techniques to Trish! Found Pinky McKay's "Sleep (ing?) like a Baby" to be super helpful!

Goodluck!