Thank you for writing in, please clarify first what do you mean by developed my content, is it a page you built on Cornerstone or do you mean you edit a template file (.php file) directly on the parent Theme?
If its a page content that you built in Cornerstone, then that is fine, you can install and activate the child theme and your content will be fine.
But if its a template file, then install the Child Theme first, then copy the template files that you modified from the parent theme to child theme in the same directory path, then activate your child theme.
How To Setup Child Themes
Customizations - Best Practices