You've got a great set of carrier for a newborn! Two points:
1) Check out the Kozy website for instructions on how to do the high back carry with a newborn. Talk about liberating, to be hands-free with baby on your back!
2) With the Hotsling, use a tummy to tummy position or a semi-seated reclining position, but don't put a newborn in a pouch in a cradle position that forces her chin to her chest. There's a risk of positional asphyxia. IME, too, many babies (mine included) don't much like a cradle position anyway.