After receiving the credit card, there is no clear stipulation that it must be activated within a few days. Usually it only needs to be activated within the validity period of the credit card.

If the bank stipulates the activation period in the card opening letter when issuing the card, then the cardholder needs to activate within the relevant period. Different banks have different regulations on the activation period, and the actual regulations of the relevant cards shall prevail.

Once the credit card is successfully activated, it can be used immediately, including but not limited to offline card swiping and online transactions, because the bank will monitor the cardholder's card use behavior in real time.