First, look at the NPC. Can you afford what the college thinks you can afford? If not, do not apply ED; you already know that any financial aid will not match what you want to pay.
Second, is it a “meets full need” college? If it is not, do not apply ED; your need may not be met.
If, however, the college meets full need and the NPC looks good, AND your child’s stats fall in the middle 50% or top 50% for the school, applying ED may be a great strategic move. It may improve your child’s chances of admission.
Yes, some ED spots will go to athletes, legacies, and other niches the college wants to fill in order to be financially, racially, culturally, extracurricularly, and geographically diverse. I do not know whether that will work in your child’s favor or not. But some ED spots will go to typical “unhooked” applicants as well, at all income levels. I know people with no “hooks” who were admitted ED to strong colleges and were happy with the financial aid package they received.
I recently listened to a phone call for alumni at Williams College. I was so impressed with the efforts they are making to ensure that every admitted student can afford to attend Williams, and they are 100% need blind for admissions. The call took place in January, right after the December ED admissions, so that was a major topic during the call. The dean of admissions and financial aid spoke specifically about how financial aid is the same for both ED and non-ED students and how they never want any student who is admitted ED to have to not attend because of finances. They are extremely generous, flexible and caring, in making sure that the admitted students can attend. But they can afford to be.
Some top colleges admit a fairly large percentage of the class early decision (sometimes almost 50%), so it really does improve the odds to apply early. But more people are admitted RD, so you should not feel pressure to apply ED if the EFC is not right.
So, the summary is, if you think your estimated family contribution on the net price calculator is manageable, and the college is one of the colleges that meet full need, apply early if you have a college you would be happy to attend if admitted. But if the EFC does not sound right or the college does not meet full need, it is safer to wait for the RD round.