Milestones

So those things are more 6-8 months for sitting. Rolling can happen at any time.
No saying mumma dadda yet but soon.

But every baby is so different. I find that some are more verbal, some are more physical, but they can only learn one new skill at a time. So can forget stuff they've learned and then relearn it too!

Yes exactly what said. My little one started saying dada a week before he turned 6 months then started rolling after that both ways. Before he could only roll front to back from 3-4 months but had stopped that and blowing raspberries and screaming when he learnt to sit up which he did from 4.5-5 months. Now he's stopped saying dada (not saying mama yet ) and he's shuffling on his knees - his version of early crawling but he is not very bouncy on his legs and he likes food but doesn't eat more than 2-3 small spoonfuls if that.

These babies will do what they want when they want. There are things you can do to support different areas of their development though. Like when I saw he was trying to sit we:d play for short periods of him sitting in my lap or with cushions multiple times a day to help strengthen his sitting posture. He turns 7 months next week Thursday for context.