Baby sleeping bags - not for new-borns?

[Hoonette]

I'm pg with our first dc and a bit bewildered by all the differing advice out there. Baby sleeping bags look like a great idea, but I think I read somewhere you're not supposed to put new-borns in them; you should wait a few months. Anyone know if this is true? Do you recommend using them straight away?

they have to be over 10lbs before you can use the 0-6month grobags

Ours say over 7.5lbs, maybe they have changed design?
Mine were both over that at birth anyway. DD1 started in cellular blankets but she was a pain and wriggled they off, grobags worked much better for us.

I literally asked my health visitor this this morning - she recommended the sleeping bags for newborns and said they were good as they won't slip over the baby's head.

I have a newborn baby sleep bag that I haven't used simply because cellular blankets are easier. Yes baby kicks of blankets but that is when she was feeding or changing.