Early Morning ADR at Magic KIngdom
(Overland Park, KS USA)
"I have a ADR at 8:10 AM and park opens at 8:00 AM will I be able to get in early or before Extra Magic Hours?"
A Separate Line
There is always a separate line for early morning ADR's (Advanced Dining Reservations) at each park. If you have an ADR before the park opens, or right after it opens, you go over to that line, they will let you in 15 minutes or so before your reservation time.
Go Directly to Jail...
Now that doesn't mean you can run ride a ride before the park opens. The rides don't open until the park does.
You will be allowed to meander to your restaurant. Even during Extra Magic Hours there are checkpoints where they will ask you to scan your MagicBand and prove you have a reservation or are a Disney Hotel guest.
There are Cast Members along the way that will help you go directly to your restaurant.
Dad's Bottom Line
So, the answer is yes, you will be able to get in a few minutes before your ADR even though the park isn't open yet. It's a cool feeling to walk down Main Street with no crowds.