7 1 1 is a telecom operator in Thailand, providing mobile phone services and calling cards. As far as I know, 7 1 1 calling cards can be used after purchase, and there is no specific activation period. Therefore, you can start using the calling card immediately after purchase.

However, it should be noted that the calling card may have an expiration date and a use period. Some calling cards may be valid for a certain period of time after purchase, such as 30 days or 60 days. If you don't use the calling card within the validity period, the calling card may be disabled or invalid. Therefore, I suggest that you start using calling cards as soon as possible after purchasing them to ensure that you can make full use of calling card services.

In addition, different calling card packages offer different services and prices. Before buying a calling card, it is recommended that you know the package and usage requirements of 7 1 1 in detail, so as to choose a calling card that suits your needs.

In case of special circumstances or more detailed questions, it is suggested that you directly contact 7 1 1 customer service or go to the local 7 1 1 service point for consultation.