Hi S.,
You can wait as long as you want for solids. The purpose of introducing solids at this stage is to get him used to different tastes and textures and so practice moving it from the front of the mouth to the back with the tongue. There is no "need" for food at this point because breast milk or formula provides all the nutrients your growing little bundle of joy needs. With my first, I really had no idea what I was doing, nor did I do much research and started him on rice cereal at the Dr's urging at 4 mos. He hated it, but thinking Dr knows best, we kept at it. He was perfectly healthy in everyway, so he didn't need it. With my second, I knew better and just breastfed her until she was really interested in our food, and then I started her on babyfood (most of which I made simply by steaming the veggie I wanted to give her and pureeing it in my magic bullet; a great money saver when you are starting on baby food; also you dont have to start with cereal, you can start with something easy to mush like banana, avacado, or unsweetened applesauce). Most importantly, although Dr's are well educated and well trained, you are well educated and well trained on your baby, so if you feel waiting is better, just wait, or tell the Dr you would prefer to wait longer. There is no harm in that. Most all the time your instincts about your baby are right. Also (I know, this is long, so this will be my last point) two months in a 6 month old baby's life is a very, very long time (1/3 of his life actually) so that gives all those little baby organs lots of time to develop more and be ready for what's to come. Good luck! :)