Hi there,
The ladies have already given you some great advice. It really is the best thing to hold off until the 6 month mark. Even at 6 months, many babies are not ready. With allergies as well as reflux, I would definitely not intro solids into the mix right now. Even with babies who have none of these issues, the digestive system is not really equiped to deal with anything other than milk at this stage.
The FAQ that Meggie posted contains some excellent information. Please read it and see what you think.
As regards the reflux, what meds is your lo on and how are they working for him?
You didn't specify how you are feeding, breast or bottle. Riley was intolearant to milk, but we continued on to have a successful nursing relationship. If using formula, which one are you on?