There are a lot of college application admission options. It’s a bit daunting at first: should you apply “Early Decision,” "Early Action," "Early Action Single Choice," or "Regular Decision"? Probably the best first step is to go to the website of each potential school and review the applicable restrictions and deadlines. If you want an up to date list of which schools offer these options (or a combination of them) go to: http://www.nacac.com/college-search/search.cfm. In the meantime, however, it's not a bad idea to gain a general sense of how each of these options works.
Early Decision (ED) is for high school seniors who wish to apply to their top choice school early, learn of their admission status early, all with the understanding that if they are accepted, the decision is binding, should the school meet their financial aid needs. Students taking the ED path should be sure the school is truly the best fit academically, socially, and personally. ED is a serious commitment. In any case, you generally know the outcome of your application by December 15th. If you get in, you must withdraw all the other applications you've submitted.
A number of California colleges offer Early Decision options including Cal Poly San Luis Obispo and Pomona; most of the Claremont schools: Claremont McKenna, Harvey Mudd, Pomona College, and Scripps; and Occidental. Some schools, including Claremont McKenna and Middlebury, offer a two-tiered ED option. At Claremont McKenna, the ED I application deadline is November 15th (with candidates notified by December 15th); the ED 2 application deadline is January 2nd (with candidates notified about admission by February 15th).
Early Action (EA) is, in my mind, preferable to ED for the simple reason it's not binding. There is no obligation on the part of the student to accept an early action college admissions offer. Better yet, though most EA deadlines are usually November 1 or 15, meaning EA applicants are usually notified by December 15th, students have till May 1st, the national common reply date, to notify the school with their decision. California schools offering EA application options include Cal Tech, Pitzer (one of the Claremont schools), and University of San Diego. You can, depending on the schools, apply to more than one EA. Before you do this, however, it's a good idea to read the school's specific EA policies posted on its website. You don't want to abuse EA, or a school you're sending an EA application to; that would be counterproductive.
Certain highly selective schools, like Stanford and Yale, offer early action single choice (EASC). Like EA, it's non-binding. If a student applies EASC, he cannot file any other early action (EA) or early decision (ED) application. The student, however, is free to apply anywhere for "regular admission".
Most applications, of course, are submitted for "regular decision" (RD). Deadlines typically run from mid-December till mid-January (with one exception being the University of California system, with a November 30th deadline). Most schools respond in mid-April, and the applicant must commit by May 1st.
One more admissions option worth noting is "rolling decision". A school with rolling decision reviews applications as they are received and offers decisions on a first come, first served basis. A number of the bigger state schools, including some of the Cal State schools, offer "rolling decision".
You now have a good sense of the various types of admission options you might face. Again, if you fall in love with a school, then, it might be worth applying early. Statistics indicate your chances of acceptance are usually higher if you do. In the end, however, it's not how you apply, but what you gain once you get there. So look hard at the schools that truly make sense for you, and then chose the type of application option that best suits your needs.