starting to get on all fours

My lo will be 5 months old on the 2nd and he just started rolling everywhere and now hes starting to get on all fours but only for a few seconds. my question is how long was it before your los starting crawling after they started doing what my son is? I cant wait until he can crawl cause he loves being on the floor but he gets so fustrated when he cant move on his own.

my daughter took forever to crawl. She did the all fours things for months before she crawled.

I think around a month? Maybe less, she would rock, then move her legs but not arms, hehe.

About a month until he army crawled at 6-7 months. He could get around everywhere army crawling, but didn't do the 'proper' crawl till 9 months.

About a month for both of them.

He started getting up on all fours at 4 months. Two weeks later started doing a worm style crawl and then at 5 and a half months was doing an actual crawl. So about 2 weeks to start moving and a month and a half to actually crawl