madmarriednika - you don't DO anything and you stop worrying.
There is a small body of research that shows that some children with dyspraxia would not have crawled. This is because crawling involves information crossing the midline of the body and apparently this is quite complex and one of the areas that dyspraxics battle. BUT the overwhelming majority of bumshufflers have no problems whatsoever at all.
You wont make a bum shuffler crawl, they find their own way. My HV said to me that they often walk late because they arrive at their destination in the sitting position so don;t have to get up, unlike crawlers.
So, my daughter bum shuffled, walked late had speech delay - connection? My opinion, big fat zero. Why? My DP bum shuffled, walked late and is academically not brilliant but absolutely amazingly clever with his hands, astounding spatial awareness and able to make most anything with a bit of wood and a chisel. I bum shuffled, walked at 9 months, have no common sense, completely cac handed, can't tell left from right and have a PhD in genetics.
If you can draw any conclusion from that you are a better scientist than me (not difficult ).
So, don't do anything apart from be glad that he/she wont be wearing the knees out of her babygro's