Early decision is an admission plan that obligates you to attend the institution if accepted.  Early Decision I applications (ED1) are usually due in early November, with notification in mid-December.  Early Decision II (ED2) applications are usually due in early January with notification in February.  Because early decision is a binding commitment, it only makes sense to apply to a school this way under the following conditions:

• You're a competitive applicant
• You are absolutely certain you'd attend if you were admitted
• You don't need fall semester grades to strengthen your candidacy
• You're not dependent on financial aid or are willing to forgo your ability to shop around for it
• You're not precluded from applying to a school this way based on the early admission policies from schools higher ranked on your list

College Kickstart handles this automatically each time you create/refine a plan, so all you have to worry about is (1) how you rank your schools in order of interest, and (2) the degree of commitment to you have to attending your top two schools if admitted.