If I let him I think he'd eat the whole 1/4 cup "serving size" that the box suggests. That seems like a lot of food, plus a fruit or veggie cube on the side.
How much does your LO eat? We started one meal / day at 5 months and worked up to 3, but "lunch" is just 1 cube of veggie and 1 cube of fruit. He's getting cereal/fruit in the morning and cereal/veggie at night.

Re: how much cereal at 6-7 months?
Just in case, I had to look it up, 1/4 cup = 4 tbsp. DD has been eating solids since just after 4 months. She has 1 - 1.5 tbsp of barley and1 container 1st foods veg. and 1 - 1.5 tbsp of oatmeal and 1 container 1st foods fruit