Ds1 was 12.5 months
Ds2 was 18 months
Ds3 was 13 months

Ds1 Crawled at 8 months
Ds2 Crawled at 6.5 months
Ds3 Crawled at 10 months..

Anywhere up to 18 months is ok for walking I think they recommend getting a check up if they aren't walking by 18-19 months though to make sure all is ok..

They all get there in the end