I always have reflux and nausea, and it generally hits about 1am. I don't usually vomit, however.
But don't assume your flush as a failure. Have you passed any stones or sludge yet? The olive oil/citrus mixture very likely did its thing before you vomited. It prompts the liver and gall bladder to discharge in the hours or two after drinking it. By the time you threw it up, it had already caused your liver and gall bladder to empty.
If you do another in a few weeks, use less oil and citrus. Some people even do them during daylight hours rather than at night, and don't go to bed.