Flipping

Hi mummies, at what month does your LO learn to flip? My LOp have flipped a few times successfully at 4mo and sometimes unsuccessfully (guessed he is still learning). However he have stopped flipping and doesn't bother to try. If we put him at tummy position, he doesn't want to stay in that position for long. I understand that babies have to learn to flip then can proceed to crawl, sit etc? We always let him flip and tummy time on the bed, should we change to let him practise on the floor instead?