i am going to disney for 3 days?

If you will be using Magic Hours, then that is how to figure out which parks on which days. Look at the calendar on Disney's website when it comes up. There should not be any major crowds that time of year. So it won't make a huge difference which days you go where.

It's difficult to do Magic Kingdom or Epcot in 1 day, so just be sure you have a bit of a plan.

It looks like you still have time to plan. I recommend the book 'The Unofficial Guide to Walt Disney World'. Don't let the book's large size intimidate you, it will tell you everything you need to know and you have enough time to read through it and plan accordingly. I grew up going to the parks all the time but decided to get the book so I could plan better and I ended up having the best vacation thanks to it, and I have used the plan I created every time since. Tons of tricks that literally shaved 4-5 hours off every day so I had more time to go on the rides again and again. You should be able to get it on Amazon pretty cheap, it's worth the read!