You can use this position with any age baby, though there are differences with how you position your baby's legs and support his head when he's a newborn.
Up until around 3 months old your baby's legs need to be as wide as his pelvis, knees higher than his bottom. They can be inside or outside the pouch, whichever seems most suitable for him.
After around 3 months old he'll be able to wrap his legs around you so keeping his legs outside the pouch, you'll need to spread them wide, but still ensuring that his knees are higher than his bottom.
Newborn babies will also need their heads supported in this position. You can do that by using the top of the pouch of the sling itself or use the tail of the sling or a muslin to wrap in the top rail of the sling's pouch.
1. Put on the sling ready threaded with the rings up 'too high' on your shoulder. When you put your baby in you'll find that his weight will pull the rings down to the perfect position. The pouch needs to be wide enough for your baby to sit in but not too wide or else you'll have lots of tightening and adjusting to do. After a couple of times you'll learn what the perfect size is. Ensure that the 'wall' of fabric next to your chest comes from the rail furthest away from you, next to your arm and it's nice and snug against you. The 'wall' should take up to about a third of the pouch, so it'll be lower than the rings, somewhere between your chest and your belly button.
2. Hold your baby against your shoulder in the burp position.
3. Keep one hand on her back and lower her down your body. With your free hand reach up under the pouch and gently guide her down.
4. The pouch of the sling will now be behind the back of her knees so she's in a seated position.
5. To secure her in the pouch you'll need to lift the top rail up over her back. so her bottom rests in the seat of the pouch.
6. Make sure that the fabric is evenly spaced from under her knees to her neck. Lean forward slightly holding your baby's weight with one hand and reach between you making sure that the bottom rail is pulled up nice and high and the fabric isn't bunched up. Then check and adjust the fabric so it's even and smooth along the rest of the pouch over your baby's back.
7. When you're done, still supporting her with one hand, bring your baby back close to you and pull the loose pouch fabric along from the top of the pouch from the side opposite the rings right along to the rings.
8. From here, hold your baby's weight in one hand and pull the part of the tail closest to your baby's head up and out until the slack has all gone. You'll need to work your way around the whole tail, section by section. In this position, even if she moves around she won't be able to wiggle out. Your baby should be snug and secure and you should feel able to let go. If you don't then check again and tighten each part of the tail in turn until you can let go. You don't have to carry her hands free but if your baby is well positioned you should feel confident enough to let go without fear of your baby falling out.