Babies are smart little creatures. They'd turn away and pull out once they're done, and while cry and whine if they're hungry. Also, as they get older, they get better at feeding at the boob so this translate to faster feeding time. If you feel that you haven't empty yourself out, pump and store the rest :) Also, it's widely recommendes that babies start their solids at approx. 6 months. Be sure to lookout for the telltale signs that he's ready. http://kellymom.com/nutrition/starting-solids/solids-when/ Also, it's important to note that up to age of 1, baby's main source of nutrient will still be from his milk so do not use his meals to substitute his feeding. Expore your baby to different variety of textures, taste and smell.
You can look out for the following signs to see if your baby is getting enough nourishment from breastfeeding: 1) Your breasts feel softer after nursing, because your baby has emptied some of the milk. 2) After a feeding, your baby seems relaxed and satisfied. 3) Babies lose some weight after birth. A well fed baby would gain back his or her initial weight loss after birth, and continue to gain weight at a good rate. You can start baby with solids around the 6 months mark. Try simple things like single grain baby cereal or pureed fruits and vegetables.
thanks