I know this procedure. But confuse me, I did not get P4 but were allowed to book a date, which is different from what I am aware of. Without P4, even If i booked the date, I am not positive that the medical center will take my request. And keep bothering me even more, the CGI webiste now tells me I reached page viewing uplimit and I have to complete the interview in this session. But, I am looking forward to potential better slots (next week) available. So I am asking if I schedule an interview date now, am I freely to cancel and reschedule? Yes, I will do my medical at Guangzhou.