If you want the maximum exposure then the three month is the way to go. With that package you will get, not only your blog or shop button in my side bar, but a featured post/guest post and mentions with links to either your blog or shop on twitter. And, If you choose, a giveaway (who doesn't love one?), or a review.
Advertising begins as soon as payment received.
If I can help you send me an email at aunt(dot)email@example.com.
I can't wait to feature you!