Turkish Airlines check in hours at IST
 

My flight departs IST for Chicago at 6 am on the last Thursday of this October. I read that passengers heading to the USA have to go through extra security screening. I am thinking about arriving at IST around 10 pm the night before so I can check in and relax at the Turkish Business Lounge until boarding time.
Will I be able to check in 8 hours before departure? Will there be any agent at the counter to check me in? Is the counter open 24/7? I understand that there is a separate check-in desk for Business class passengers.
Please advise. Thanks!

You can't check in the night before because you need to go through additional security/visa questions just before check-in (which is done by Gozen) and they only start the process around 3.5 hrs before the first flight to USA/UK/Canada in the morning. That's why you also can't go to the lounge.
Are you coming from another flight? I had luck with some out stations before where I was issued a boarding pass, but some others couldn't because of this security step.

If there is an Israel flight at a similar time, Gözen aviation security agents would be present at the dedicated check-in counters.

Why do you wish to arrive at the airport this early? Spend the day/evening in the city and around midnight or later, take the airport bus or a taxi to the airport.

There is a TK157 scheduled 10/27 1:30 am to Miami, so check in to USA should be open, but I have no experience if they will accept your bags and issue you a boarding pass that early.

I was able to OLCI and get a mobile bp 24hrs before departure to ATL so maybe OP (provided they don’t have checked bags) could indeed make it airside and do the security check at the gate.