Hi, you can start at about 1 year old, but put less salt for your baby. Even 10 months old, if your baby can it pieces of food and not pureed anymore. When you cook, keep the part for your baby aside and you only need to add the salt at the end of cooking for yourself. Then just use scissors to cut the food in small pieces. But your baby still needs to eat food that is cooked very softly.
As for self feeding, my daughter is 19 months. She can self feed with a spoon since she's about 15 months, but it takes time. So what I do, I give her a spoon and let her feed herself and I feed her in the same time. You can start doing it with your baby so she can get used to it.