That's the reason you dissolve the DGL in your mouth 20 minutes before you eat, it needs that much time to take effect coating the esophagus. Someone researched this and it looks like they came up with that time frame.
The soup recipe I posted is very thick with vegetables, there's not that much broth. I don't think it matters much though even if it's a broth you eat with something in it (for example, chicken soup) take the DGL and then have it. It's not like you just eat soup everyday.
The main reason to limit the drinking is to avoid taking alot of air into your system.
Heartburn and Indigestion During Pregnancy | Caremark Health Resources
This is informative even though it's directed at pregnant women.