DS just turned 7 months and I feel like he is on the brink of army crawling. He's trying to figure out the coordination needed, but isn't quite moving forward yet. He's able to bend his legs and push. He's so close. But he isn't quite able to sit up yet. He can sit up for a second or two only if he's holding on to something or using a hand to touch the floor and balance himself. My first son was able to sit up well before he crawled, so this seems a little strange to me.