Hello Adil, Which Android device are you developing for? If it is a Zebra Android device, you may be able to make use of the EMDK for Android's Scan And Pair API. Here is a tutorial to walk through the process, it doesn't exactly match your use case, but it should provide enough info to get you started.
I'm printing using Samsung Galaxy Note 3 device running Android version 5.x (Lollipop)
Does your app use the Link-OS™ Multiplatform SDK | Zebra ?
It has BluetoothConnectionInsecure class that establishes an insecure Bluetooth connection to the printer.
Insecure Bluetooth connections do not require the devices to be paired, thus you can print to the ZQ520 without having to press the accept button on the printer.