3 SAT Subject tests on the same date?

I am intent on taking the World History, Chemistry, and Biology M SAT II Subject Tests. However, I am not sure how I should do this.

Why now? Why these classes?:
-I am currently enrolled in these three classes with my school.
-I absolutely love World History and I am already studying hard for the AP test.
-I like Biology and score an A on every single test.
-I believe Chemistry is very easy. I asked my teacher and he said that because I possess a good grasp on the subject, I would be one of the only two students in his class that he would recommend to take the SAT II Chemistry test.
-I want to major in neuroscience, and I believe that Biology and Chemistry will show colleges my mastery of this subject.
-I meet the requirements for these three SAT II Subject tests.
-I would rather take them all this year so I don’t interfere with my plans for the summer and next year.

However, I have some questions:
-I want to get perfect scores on all 3 of these tests. I am planning to buy a Barron’s study book for these three subjects. Should I buy them? Should I buy one for World History even though I already have a study guide for the AP World History test?
-Is taking three SAT II tests in one day exhausting? It’s only 3 hours, so it can’t be as bad as the SAT. Will it mess up my score, even though I have a very resilient mind?
-I read somewhere that if I take these tests all on the same day, I need to send them in altogether (I can’t leave one out). If I get an 760 on World History, and 800 on Chemistry, and a 750 on Biology, will my chances of getting into Harvard be severely reduced?
-If I send in two scores on the same SAT II test, like a 750 on Biology then an 800, will colleges override the 750 score or will they think that I am not qualified because it took me two tries?
-When I buy the Barron’s books, I plan to read through the entirety of them. I have 3 months left until the test. If I, on average, have extracurricular activities for 3 hours a day and no hours on weekends, do you think I could finish all these while gaining the most from them possible?
-I would say that I am the smartest student in my grade for Chemistry (it is literally the easiest subject I’ve ever taken, except only 3 people got an A in my class last semester), and for World History (I love it and I enjoy studying for it. I don’t usually read nonfiction books, but I like reading about history). For Biology, it is pretty easy but I rarely study because it is so easy. I attend one of the top schools in the country. I absolutely know that I you won’t be able to give me an exact score, but what do you estimate I can score, out of 800, for these SAT II Subject Tests?:
-World History (I love the subject and I am constantly engaged in class, and I am studying vigorously for the AP exam. I might read the Barron’s book))
-Chemistry (It is one of my easiest subjects, I am the top performer in a competitive high school. I will read the Barron’s book)
-Biology (It is pretty easy but I don’t put enough time into studying. I will review all my notes and read the Barron’s book)

Thank you!

From what I know, if you take multiple subject tests on the same day you can keep all scores or cancel them all. However, with score choice you can choose to hide one or more subject test scores when you send them to schools.

Considering the humblebrag about how smart you are, how easy the subjects are, and how amazingly good your school is, I think you a;ready have a good idea of what you will score. If you’re really unsure, and not just posting for validation, take a practice test. No one other than you can know what score you’ll receive based solely on your descriptions of your effort and love of the subjects.

I am so sorry. It really looks like bragging. I apologize. I just never though about these tests before and I wanted to know more. I hate bragging and I wish I could edit the post. I just wanted to articulate my true feelings about the subject, but I read it again and I apologize.

And the checked the SAT website and it said this:
Students are only able to select which scores they send by test date for the SAT and by individual test for SAT Subject Tests

So that question is answered, sorry I was mislead. Thank you so much!

My kids have taken 3 on the same day and not come out drained like they do after full SAT.