Sarah is 5 months and 2 weeks (will be 6 months on September 24) and she is already able to sit up for short periods of time. Bekah didn't sit up very long until right at 6 months. I think it has everything to do with the use of the Bumbo. It forces her to strengthen those muscles.
Bekah fell asleep on the way to an errand with Bobby and Sarah at 3 pm today. She didn't wake up till 6 pm. She had panties on the whole time. She stayed dry. I sat her on the potty to try to go. She sat for 1 hour and never went. I put a pull-up on her because I needed to feed Sarah and Bekah didn't want me to leave the bathroom. I fed Sarah, got Bekah's dinner and played with them for a while. Bekah is still dry. About 8:15 pm, I tell her that we need to try again. We go in, she goes almost immediately, but not as much as I would have gone if it'd been 5.5 hours since I went to the bathroom. Man, she has a big bladder!!