Index: src/wp-admin/includes/schema.php
===================================================================
--- src/wp-admin/includes/schema.php	(revision 38982)
+++ src/wp-admin/includes/schema.php	(working copy)
@@ -518,6 +518,9 @@
 	'medium_large_size_h' => 0,
 	);
 
+	// 4.7.0
+	'fresh_site' => 1,
+
 	// 3.3
 	if ( ! is_multisite() ) {
 		$options['initial_db_version'] = ! empty( $wp_current_db_version ) && $wp_current_db_version < $wp_db_version
Index: src/wp-includes/default-filters.php
===================================================================
--- src/wp-includes/default-filters.php	(revision 38982)
+++ src/wp-includes/default-filters.php	(working copy)
@@ -188,6 +188,11 @@
 // Email filters
 add_filter( 'wp_mail', 'wp_staticize_emoji_for_email' );
 
+// Mark site as no longer fresh
+foreach ( array( 'save_post_post', 'save_post_page', 'wp_ajax_save-widget', 'wp_ajax_widgets-order', 'customize_save_after' ) as $action ) {
+	add_action( $action, '_delete_option_fresh_site' );
+}
+
 // Misc filters
 add_filter( 'option_ping_sites',        'privacy_ping_filter'                 );
 add_filter( 'option_blog_charset',      '_wp_specialchars'                    ); // IMPORTANT: This must not be wp_specialchars() or esc_html() or it'll cause an infinite loop
Index: src/wp-includes/functions.php
===================================================================
--- src/wp-includes/functions.php	(revision 38982)
+++ src/wp-includes/functions.php	(working copy)
@@ -3241,6 +3241,16 @@
 }
 
 /**
+ * Delete the fresh site option.
+ *
+ * @since 4.7.0
+ * @access private
+ */
+function _delete_option_fresh_site() {
+	delete_option( 'fresh_site' );
+}
+
+/**
  * Set the localized direction for MCE plugin.
  *
  * Will only set the direction to 'rtl', if the WordPress locale has