Looking for official advice about Personalized Spots, can you help me?

I'm writing a manga/book and want to start a spot based on it to get some people familiar with my work, and hopefully win over some fans,(so long as advertizing is allowed), but I'm serious about publishing it. What concerns me is the threat of anyone stealing my ideas to use as their own, before it's published. I was told that it is best to have your work copyrighted only once it's finished and prepared for publishing, which my work isn't even close to that. I WANT to advertize, and share but I don't want to lose any of my original ideas or my work because it's not copyrighted. Does anybody have any advice as to what I should do, would it be safe and or a good idea to make the spot or no and wait? What would you do?