So far, I didn't experience it either! I am always complaining that I have not enough time to write all the things I wish to write. I have more than a dozen of small notebooks with "ideas" as I always carry one around to jot down my thoughts. Some of them I revisited and developed into a poem or a short story, others I just waiting to be picked up.
Sometimes I use an app on my phone to write some ideas or if I am at home, I write them on my File. And obviously some ideas come in the most unexpected moments, like when I'm in the shower, laying down on my dentist's seat, driving or having my both hands busy.