Talk

TICKS

IIRC:

Tight (no slack on the carrier, for a small baby bum should be higher than your bellybutton)
In View (face in view)
Close enough to Kiss
Knees higher than hips - legs should form an M position.
Straight back (when you press a hand gently to their back if they uncurl, they're too loose. Also applies to ring slings/pouches/bag slings - their back should be straight, they shouldn't be lying in a hammock.)

Two fingers under the chin thing mainly refers to the I and S points - their airways need to be clear, chin off the chest, preferably able to move their head backwards, if they can support it themselves. But you can see if they're "in view" whether they're managing to breathe happily - grunting or snuffling isn't a good sign.

TICKS! That's it.

Thanks Bertie.