Last feeding before the upper GI test

I'm up feeding Tristan (I had to wake him up!) for the last time until after his GI test at 7:30 4 hours from now. It's going to be hard to hold him off that long. He'll get the barium stuff during the test and I'm praying he likes the taste and that it satisfies him during the test so he's not upset the whole time. I'm really dreading this!