T for Timely, Time-based, Tangible and Trackable.
When you create a goal, there needs to be an end point to give a clear target for you to work towards. If you don't have a Target (hey, another T word), your goal is no longer SMART--it becomes vague. Why is this? Because without an ending, you can start any time. There is no built in urgency, so why start now?
When choosing a time frame, use many of the same aspects of a SMART goal. Your time must be measurable, attainable--and realistic. It would be great to start and finish a novel by the first day of spring, but how realistic is that for most of us? Is it attainable--oh, perhaps--if I don't go to my day job, interact with family and friends, or take showers. However, it is a reasonable, stretching goal for me to say I will write one chapter a week to take to critique.
One of the more difficult aspects of the T is striking a balance between having enough time to achieve and giving yourself too much time. Planning for too much time has the same result as not setting a time frame at all. Take my weekly chapter. Doable. I've done it before--just not consistently. But what if I change my goal to say I'll do one chapter a month for critique. How much you wanna bet I wouldn't even start that chapter until the last week of the month? There's no urgency until then. And, such a goal wouldn't stretch my abilities at any time--except that one week.