I agree wrapping is the way to go for the first 8 weeks then you can start wrapping under the arms during the day when it is warmer and introduce the grobag at night once you start wrapping under the arms. They don't roll around so much until about 3 months so don't get uncovered.

I love grobags and used them with DS until he moved to a big bed at about 2.5 yrs.

My DD didn't have any problems moving to the grobag (we got a 1.0tog for summer at first with her) as she had been getting her arms out of the wrap. I think they feel secure in the grobag, saves heaps of washing of blankets and you have a good idea of the warmth they are getting for the temp in their room.

I wouldn't put any blankets on top of a grobag because they cannot move around as much and you don't want them tangled or too hot. Put layers on under the grobag, tonight DD is just in long sleeve suit with a singlet and it is 21 degrees in her room. As it gets cooler I will add pants and also a pj top, or a heater to increase the room temp. We bought a little electronic temp so it was easier to work out than using the grobag temp card that comes with the bags.

All the best