@Antoni ********
When I booked the appointment online, the earliest availabilities were a month later. Right now I see 12 September as the earliest one. Doesn't sound too bad!
But sometimes they add availabilities a bit more last minute, like right now you can see the 4 September as example. For the same date, they have the normal time slot of 09:00-12:00, and then they later added one called Additional for 11:30-12:00.
You could book the 12th now, or take a chance, wait and check every day to see if they add availabilities earlier.
Good luck!