Jack sitting up almost 21 weeks

Jack has been hitting the milestones lately. He'll be 5 months on March 13. He's a little rolly-polly now. When he's on his back his rolls himself around either on his back or flips himself over. He sat up on March 7. I steadied him and then he stayed up for a few moments. He must have really liked it because now he can keep himself up for minutes. Here's a picture of him on March 8 showing off at Gymboree. He's also creeping around (sometimes with help). When he has a bolster (pool noodle) under him he takes off. He just has to figure out how to keep is body up and he'll be off!