Honestly - I'd give neither wait for a while! Rice cereal is really hard to digest (UK guidelines are not to use brown versions with little ones as they are more filling and can stop them getting enough calories because they will eat less of it) and can cause constipation which also makes reflux worse.
We started my DS at 5 months and it made his reflux significantly worse. It did help my DD, she was pouring out her milk so a couple of spoonfulls from 5 months helped keep her reflux milk down - if she was silently refluxing like her brother at that age I would have left it until 6 months and started BLW.
Laura