wordpress.com to workpress.org permalinks

Not sure if in the right forum, but I’m exporting a blog from wordpress.com to wordpress.org, and want to maintain the same permalink structure and internal links. When I import the wordpress.com xml file in my new wordpress.org blog, my permalinks change from the /year/month/day/postname format to the /blog.com/?p=number format. How can I have the import maintain the original format and links? I tried searching the posts here but not sure if any address this issue.