1. On Google+ get your user id from the URL (the large number):
This will provide you with an instant RSS feed of your public Google+ updates.
3. In your WordPress blog go to Appearance > Widgets > RSS Feed and paste the feed URL.
That’s it :-)
Apparently the default frequency with which the RSS widget updates is every 12 hours. If you want to change you can add something like this to your theme’s functions.php:
add_filter( 'wp_feed_cache_transient_lifetime', create_function('$a', 'return 1800;') );