By design, Smart Campaigns wait a set number of days you specify between steps before sending the next message. This way, they're perennial and reusable.
However, many of our clients still use it to promote time-sensitive events and see phenomenal results. Of course, this requires a little more planning. When applying a campaign, you'll have the option to set when it will begin. From there, you'll just need to do a little math as to which day the following step will fall on.