I had a few before I knew what they were, and they were all within the span of a month or so. Once I learned what they were and started to try to have them (about a week ago) I've had one, and that was two days ago. Sadly i was too excited and and woke up the moment I realized I was dreaming. All the other times I didn't know that it was possible that I could control stuff so I didn't take advantage of it.