My DD started bumshuffling at about 10 months and she walked just before 18 months. She never crawled and didn't pull herself up on things until she was over 12 months.

I have been told it is normal for bottom shufflers to walk later. They are mobile and upright, so perhaps they don't look for a new challenge like crawlers do.

On the upside, when DD did walk she could do it perfectly. I didn't have to worry about a wobbly toddler falling over and hurting herself.