Ours took about 25 minutes. They'll sit your kid up (our guy was 6 weeks) and they put a screen next to their head and i had to feed mine because he was so little and they watch him swallow. He had to eat 2 oz straight of thin barium, no burping. I don't know how old your LO is. If he was aspirating or choking they would have increased to nectar thicknes, then honey, etc. Our swallow study showed DS is doing great and he didn't need it any thicker, so it took them about 15 minutes to set up and the whole test took maybe 8 minutes.