Suddenly sitting and very giggly

So it seems like overnight Sophie is growing up. She is now truly sitting independently. She sat in the grass this weekend and can even lean forward and pick up her toys without falling. After about 10-15 minutes she gets a little tired and needs a change of scenery. I don't think it will be too long before she is crawling. When placed on her belly she is now getting up on her knees. No forward motion yet, but I am sure it will not be too long. I don't remember Brie sitting this early or getting mobile this quick, but I guess every baby is different and Sophie has her big sister to watch. Brie was showing her how to crawl this weekend and Sophie was watching intensely. The two of them had a ball playing in the ball pit and Sophie was just laughing at her big sister.