From about two months (when a friend recommended it) to nearly two yrs old. By that point DS was mostly walking everywhere, but I do now have a VERY cheap Tesco buggy for the longer distances when he's tired.
so two votes for kari me as an only sling.. thats good [glimmer of hope for slings re-ignited..] they are bloomin ugly faffy things though! borrowed one to try with DS and hated it Would an ergo do as an ONLY sling?
had a look and the beco I can cope with, fabrics not too... anyway!, I can't see the difference between the beco and the ergo, are they much the same? is there a newborn insert for becos like there is for ergos?
I only actually USE two - a stretchy wrap for the newborn stage (and I made my own out of T-shirt fabric so cost was low) and a mei tai style (in my case a Connecta) after that (I could probably make that one too, if it came to it, but I haven't). I did go through a couple of others while figuring that out with DC1, but fortunately there's a thriving second-hand market in slings and if you buy second-hand in the first place you can sell on for the same amount that you paid.
I wouldn't go with a Kari Me as an only sling. You can't back carry with it safely and most kids hit a point where they are easier to carry on your back at least some of the time. And whilst some people use them for a long time I see a lot of people at the sling library I run who have 4-8 month olds and feel they are getting heavy, and find a different sling comfier.
A woven wrap will do birth to whenever you like (my sister carried my then nearly-12-year-old step son on my back in one for a laugh). Because it isn't fitted at all, and is weight tested to very high weight , it can cope with the widest age range. It's also lovely and snuggly for a tiny baby. You do need to learn to tie it though.
If you want buckles a Manduca is my favourite for newborn to toddler/preschooler at a push. Prefer to the Ergo as find the Ergo infant insert a bit rubbish and too hot. Prefer to the Beco as it is wider and so supports legs for longer and prefer to the Connecta as more structured which I find adds support.
But I'd go to a sling library and see what fits you / suits you / appeals to you, if you can.
The Beco has an infant insert bit for a newborn - it just lifts them up a bit rather than a big snuggly thing like the Ergo though. The main difference between the Beco and other buckled carriers is it has an internal harness that the baby straps into, so back carries with a baby are really easy as you can strap the baby in first then put it on your back - we also found it really useful when ds was a baby in front carries as you can swap the carrier from me to DP without taking the baby out/waking him up.