Several hours after eating?

I've found that I tend to have reflux 3-6 hours after eating. Before I started having reflux, I would sometimes get nauseous around 3-6 hours after eating, too. Anyone know why it's delayed like that? It's frustrating because I'm never sure when to take my Zantac - long before meals, right before them, right after, hours after. Sometimes I will get reflux immediately following a meal if it's rich or if I eat a lot, but it doesn't always work that way. I can eat a bowl of cereal and be fine, but a couple hours later it hits me. It's really confusing.