It is indeed payed in installments. You should check your Transaction Hstory pages to see the (upcoming) payouts and there status. Unless you are a new host, the first payout is submitted the day after the guest checks-in.
@Cari31I saw that you have 9 reviews already. Your first installment payment should have been in your account in 3-5 business days unless there are payment issues.
If there are issues in payment, you normally receive email from Airbnb, please check if you have received any email from Airbnb about it. Don't forget to check the Spam folder.
You can also call Airbnb support anytime to find out.