You can check for your AMEX Card activation by clicking My Linked Accounts in the GCash App. American Express Icon will be marked in blue to indicate that its activated. Once you click, you will be able to see your virtual AMEX card which you can use to shop online, pay for services, etc.
The P20 will be seeded to your account after 3 business days upon an approved verification application. You will receive an SMS notification that this has been credited to your account.