There is absolutely no reason why holding off is a bad idea. He probably won't take more than a teaspoon the first time anyway, but this is all new and if it will make you feel better to wait a week then go for it. I remember I was so excited to start my LO on solids, but I just didn't feel it was right so I waited.. and waited... and finally when she was around 7 months I gave her some rice cereal (she hated it btw!).
Go with what your mummy instinct tells you. It seems to me that you are having your Mummy Radar on and it's telling you to just wait another week, and the Radar is rarely wrong..