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 usually be used immediately 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 usage period. Some calling cards are valid for a 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 the calling card as soon as possible after purchasing it to ensure that you can make full use of the calling card service.

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

If there are 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.