@outofplace_christian I have a lillebaby carrier and wore my first starting around 6mo, and my second child starting around 5mo, depending on neck and trunk control.
I first make sure the arm straps are attached to the sides, but not attached in the small middle crossbody buckle.
I secure the waist strap around myself and tighten it.
I lay or sit the baby in front of me, facing towards me.
I put my arms straight ahead and then rotate them like I'm turning a steering wheel sharply, then pick up the baby under the armpits.
I untwist my arms over my head, which rotates the baby to face my back, while bending over.
I reposition my hand to one pressing the butt towards me with using the other hand to make sure the legs are situated
I then use the free hand to slide my arm in the strap loop and flip it up over my shoulder like I'm sliding my arm into a jacket hole.
I then switch supporting hands and slide my other arm in the strap loop.
Once I feel the baby is secure, I let go of the butt and snap the front crossbody connection.
I then stand up
Tldr: watch a video of someone doing it