Crawling

How long after your baby showed signs of wanting to crawl did they start to? My daughter will be 7 months on the 25th. Every time she is sitting up or laying on her back she gets onto her belly and starts bringing her knees up to her stomach, but she can’t push up off of the floor. I know every baby is different I’m just curious, I also haven’t baby proofed the house yet so I guess I should do that soon? Lol