DD isn't sitting on her own yet, but she does hold my hand to help steady herself. When she sits on the couch you can actually see her trying to sit up more which gets her nowhere yet so hopefully she get the muscles to do it in the next month or two. At least that's the time frame I was given for her to be able to sit on her own.
DD doesn't sit on her own, and she is small for her age, so she even slides around in her Bumbo a little. She does ok sitting with assistance, but I don't think most babies can sit up alone until around 5 months.
My DS is 14 weeks, and I'm pretty sure he's nowhere near sitting on his own. He can sit if I prop him up. He sits pretty well in his Bumbo and his activity center, but definitely not on his own.
Re: Question for 3 mos babies
DD isn't sitting on her own yet, but she does hold my hand to help steady herself. When she sits on the couch you can actually see her trying to sit up more which gets her nowhere yet so hopefully she get the muscles to do it in the next month or two. At least that's the time frame I was given for her to be able to sit on her own.