Delay automatic updates after installation.

src/wp-admin/includes/upgrade.php

@@ -52,6 +52,21 @@ function wp_install( $blog_title, $user_name, $user_email, $is_public, $deprecat
 		wp_check_mysql_version();
 		wp_cache_flush();
 		make_db_current_silent();
+
+		/*
+		 * Ensure update checks are delayed after installation.
+		 *
+		 * This prevents users being presented with a maintenance mode screen
+		 * immediately after installation.
+		 */
+		wp_unschedule_hook( 'wp_version_check' );
+		wp_unschedule_hook( 'wp_update_plugins' );
+		wp_unschedule_hook( 'wp_update_themes' );
+
+		wp_schedule_event( time() + HOUR_IN_SECONDS, 'twicedaily', 'wp_version_check' );
+		wp_schedule_event( time() + ( 1.5 * HOUR_IN_SECONDS ), 'twicedaily', 'wp_update_plugins' );
+		wp_schedule_event( time() + ( 2 * HOUR_IN_SECONDS ), 'twicedaily', 'wp_update_themes' );
+
 		populate_options();
 		populate_roles();