In vary rare cases it happens. When Ashtavakra recited verses to let king Janak know ‘who you are?’ then at that time Janak was in state of ‘shrotapanna-श्रोतापन्न – in this state hearing is so focussed that whatever heard becomes habit immediately’. So king Janak got enlightened and Nirvaana simultaneously.
Both these happens through ears or eyes that is why they are in pair! Loss of one doea not hamper one’s journey to personal home.
In normal cases mind comes to rest for a fraction if second only called ‘satori’ in Japan. It may happen alone in rare case but generally it happens with the help of other object or person. Like Lao Tzu got when leaf was falling, Bulle Shah got when his curd pot fell in dream! Osho got its glimpse in eyes of a girl.
Then by practice it happens alone and then further practice one can reach nirvana. In Japanese Zen from ‘satori’ to ‘nirvaana’ the time is given for practice is 20 years. My blog at osholeela.in have more about it.