It's been my understanding that they are allowing appointments to be booked starting from those who submitted their application in March, and that you are supposed to wait for an email before you book.
What date did you submit your online application, if you don't mind me asking?
Since I submitted on April 15, I figured it was not yet my time and that I still had to wait for the official email. If this isn't the case, I'd love to know because I will also try to book.
Any insight or advice welcome!
Here's what it says on the UKVCAS website:
In order to be fair to everyone, we are now opening up the booking system in date order starting with people who registered with UKVCAS before the 27th March but did not have an appointment. We are working from the earliest to the most recent registrations as we think this is the fairest and best approach to take. If you are one of these customers, you will have an email from us on the 21st or 22nd of June asking you to book an appointment. The email will have full instructions about next actions.