When buy order you placed on "Buy Orders" panel is matched on "Sell Orders" list, buying occurs and this amount is transferred to your crypto-currency balance immediately.
If there isn't a different order that matches yours, check out our article entitled Açık emir nedir? for more detailed information.
Check out our Nasıl alış/satış emri verebilirim? titled article for more detailed info about buy/sell transactions and your balance.