From what I have seen, graduating early isn't always a positive. Here's why I think so.
Sure, you graduated early and took more credits than another person. Congratulations! However, what happens when you still take a full credit load, but have few credits? Well, those students tend to do better in their classes. That means a higher GPA.
Having fewer classes means a student will have few professors to get to know per semester. This means you can talk with them more and find out which ones can write a great LOR. If you graduate in three years, you can still get LOR, but rushing shortens the time to three years instead of four.
Being in school for three years means you also get one less year of extracurricular activities or shadowing. With taking more credits each semester, you will also have less time to devote to these things.
Let's look at two applicants, one that took four years and one that took three. Let's say both got degrees in Biology.
Three year student:
Degree: B.S. Biology
GPA 3.4
Shadowing time: 40 hours
Clinical time: 80 hours
LOR: 4
Four year student
Degree: B.S. Biology
GPA: 3.7
Shadowing: 60 hours
Clinical: 120 hours
LOR: 5
If I was on the committee, I would probably accept the second student over the first, especially if they interviewed the same. I am sure the four year student will have participated in more clubs, did more volunteer work, and been a more rounded person than just a student.
I think any benefit you made by graduating early will be cancelled out by not having more time for other activities.
HOWEVER!!! If you do graduate in three years, then I recommend taking the year off, getting a job (to make money!!!) and then beef up on those areas that you lack. The only thing you can't really add to is your GPA, which everyone here will tell you is important.