The night before my Dad passed (in 92) I saw my Nan, who had passed five years earlier, it was over in ten seconds. I was 16 at the time, ran out and told my Mum who was still up (dad had gone to bed already), she told me go back to bed, thinking I must have dreamt it, the next morning Dad was gone sometime during the night, he was 46, had not been sick, he passed from cardiomyopathy, we found out months later.
Years later, about 18 years to be exact, I was living in an old house, I woke up in the middle of the night, to see a lady standing in my bedroom door, my rush to turn on the bedside light meant I took my eyes off her, in that time gone. Later I realized I could see her plain as day in a white dress with blonde hair, in the dark...
Both experiences were very quick, not longer than about 10-15 seconds each, felt like eternity at the time.
I understand people's scepticism, but even I could not have predicted my Dad passing, hell of a coincidence.