Studybay does not have any special paydays, so you can withdraw your money at any moment if you have at least $20 on your account balance.
Once you create a withdrawal application (you can check how to do it here), it usually takes 3 business days for our accounting department to process it. If it goes through successfully, it may take some additional time for the money to hit your account but that should not take long and will depend on your bank or payment system.
If your application does not go through for any reason, the money will be returned to your Studybay account and you'll need to create another application. In such case, contact support for more information.