I strongly agree with @gibby on this one. My son applied to Yale SCEA in the early fall of last year, and it was his first choice at the time. Another school (ironically, the one he ultimately ended up at) had been his first choice for a very long time before that, but he fell in love with Yale when we visited it over the summer (and, frankly, we did too). When he got in, there was some temptation to accept right away, and I think if we hadn’t applied for financial aid, he would have—we were all thrilled, more so than with any of the other acceptances later on. But the aid decision was important to us, and although Yale’s offer was very good, we wanted to see what would happen with the schools he had applied to regular decision.
Over the course of the next few months, our son’s feelings about Yale became less certain. Although he still loved it, he was increasingly concerned with what he was hearing about the computer science department (his intended major) and its reputation outside of Yale. By March, he wasn’t sure what he was going to do. He got into his regular decision schools, all but one of which were true Yale “peers,” and all these peer schools offered him significantly more money than Yale had. Since the peer schools’ offers were in the same ballpark, we asked Yale if they could reconsider his award. They did and ended up matching that range (though they weren’t able to guarantee that the revised award level would remain the same for all four years, assuming our financial circumstances didn’t change—that concerned us a bit).
Our son then faced a very difficult decision, because money was no longer a factor and he was choosing between several great schools. In the end, he made the most “rational” choice and picked his longtime first-choice school, which has a top computer science program and, arguably, a better location. So both factors @gibby mentioned—financial aid and the possibility of changing one’s mind—came into play for us.
I do wonder whether Yale’s initial aid offer was lower than it would have been had my son applied regular decision. Maybe when students apply to colleges early action, schools feel like they don’t have to offer as much financial aid—they can offer less on the chance that students will be so happy they got into their first choice that they’ll just accept the offer. No way of knowing, but that possibility argues for waiting until all aid offers are in before deciding.
One final caveat, though: Trying to make this decision over just a few weeks in April can be very difficult—it’s an incredibly busy, pressure-filled, exhausting time, especially with travel, and I really wish students had until, say, July to make the decision. Although my son felt ready to decide in April and hasn’t second-guessed his choice, I know of students who definitely weren’t ready then and could have benefited from having more time.