I was having heartburn almost immediately. It's not so bad now at 24 weeks but I found that Zantac really helped.
I've been fighting it since 4 weeks. It's better now at 10 weeks but I still get it. I try not to bent over much. That seems to make it worse.
It's possible. Typically heartburn in pregnancy is caused because hormones relax the valve in your esophagus that keeps the acids down. It really isn't because of baby or what you eat. Those thing just make it worse later.