Let me be the 156917th person to remind you that you should NEVER GO TO GOOGLE for medical advice. This includes pediatric milestones!
For proof, I googled the major milestones and wrote down the first result that came up. Most of these aren’t too far off, but let me tell you how concerning this can be once you start googling.
I was actually surprised that it said 4-6 months for rolling. HOWEVER, there are some sites that say rolling can happen as early as 2 months. This is true, but it is not purposeful at 2 months old, meaning it was probably due to the head being bigger in comparison to the body and the top-heaviness helps a baby gain momentum. They do not actually have the strength and coordination to roll consistently at 2 months old.
I was also surprised that sitting was reported later than what a pediatric expert recommends. From a PT perspective, kids may start prop sitting at 5 months, and sitting independently by 6, however it’s not usually independent enough for parents to put their kids down and walk away. This is usually closer to 7 months.
If crawling happens at 6 months, I’d be slightly concerned that your baby hasn’t built the core strength and stability in sitting yet! Typical ranges to crawl is between 8-11 months. It can look like an army crawl at first!
Walking- first steps can happen ANYWHERE between 12-18 months. I am not concerned about a child not walking UNLESS they aren’t showing any signs of walking by 16 months.
I hope this helps clears up some confusion and encourages you to STOP GOOGLING!