If your goal is to get a photo at the top of every post, I’d encourage you to use the featured image instead. It can be added to any post type with add_theme_support():
// add featured image to Page post type
add_theme_support( 'post-thumbnails', array( 'page' ) );
Then the user can upload an image to the “Featured Image” field and you can display that in your template immediately preceding your content:
// ... the loop and stuff ...
the_post_thumbnail();
the_content;
// ... more stuff, close the loop, etc.
the_post_thumbnail() takes additional arguments that let you set whatever size you want along with other image attributes. Whenever I want to standardize image entry, this is my favorite way to go.
If you need more than one image, add a custom meta box or look into one of the plugins that comes with an image meta box like Advanced Custom Fields or Types. You can then allow for more images to be uploaded and templated however you like.
A final option would be to have people upload photos on a page so that they’re attached, and then stick a gallery immediately before the_content like this:
// ... the loop and stuff ...
do_shortcode( '' );
the_content;
// ... more stuff, close the loop, etc.