Hello Vinod, the APPGECET counselling dates are not officialy announced, i think the provided link is not correct. You can check on official website for more details for fee payment link. The link is provided below go through it

https://sche.ap.gov.in/pgecet/PGECET/PGECET_HomePage.aspx

Hello VinodKumar Sunnapalli

Sometimes they activate the link but the further procedures cannot be done through it, i.t most of the times the window does not open. If the link is opening then you can do the payment. If you are still not sure then do it after 22.8.19 as mentioned in the officia notification. 

Hope it helps you.