I also agree at least 3 hours, even more. Once you land (maybe on time, maybe not), you have to to through Immigration, then wait for your bags to arrive at a carousel (can take a while and it can be chaotic), then go through Customs (you can shop at a duty free store beforehand)-- going through Customs doesn't even require filling out a form if you have nothing to declare BUT you could ge pulled aside for an inspection anyway-- then exit security, find the transit desk, check in then go through security upstairs and go to your gate. Have you already bought your Turkish tickets so that your domestic flight would be booked separately? In that case, you may have to check-in at the regular check-in counters upstairs rather than at the transit desk (not a big deal, but you'd be under domestic baggage weight rules).