Remember Whose Time It Is.
I read a promotional message that assured me time was running out. Specifically, time was running out if I wanted to sign up for a seminar deigned to make my life/business happier/more profitable.
The time that was running out was not mine, but the sender's. They were running out of time in which to sign me up.
Time is the quintessential scarce resource and thus a potent trigger to action. But you have to ensure that the time you reference in your marketing activities is solely that of your prospects. If you don't, it won't seem truly personal and, like me, they won't sign up.