I found that Samuel started eating more at night around 4 months. I think there are a few reasons for it, one being that I realized when he eats in the daytime, he gets distracted easily, so doesn't eat as much/long as what he should. At nighttime, his focus is on eating. We're trying to resolve that.
I agree, solids should be put off as long as possible. 'Everyone' is telling us that Samuel should be having cereal now, but we're waiting for another month. If he has to eat at night, sobeit.