DD1 was self-settling around 6 months - she never took a dummy or anything and she was sleeping through from about 7 months. She is a very good sleeper still and takes herself off to bed without fuss.

DD2 is very sucky and is also fed to sleep (like DD1) but she has just discovered her thumb! She is self- settling with that and I am amazed. Different things work for different babies though so try a variety of techniques and work out what works for you.