Buying Turkish Lira before you go means you won’t need to worry about exchanging money after you land. You’ll also avoid more expensive rates at tourist hotspots, where they tend to be less favourable.
Keep in mind that when you withdraw money from an ATM, you may need to pay a foreign withdrawal as well as local transaction fees.
Buying Turkish Lira before you fly reduces the hassle of finding an ATM, haggling with exchange offices or worrying about paying tourist rates.