If you are using Google+, and if not why not, you should also be using a great Chrome app called DoShare. DoShare allows you to schedule posts to your Google+ and a whole lot more.
GPlusGeek has put together an excellent tutorial on using DoShare called: A DoShare Guide: Scheduling Google Plus Posts in Advance…And So Much More! .
I’ve been using DoShare for several months now and I learned quite a bit from the article.