This depends on the benefit that you have. 

For the Complimentary 100 Day Screen Protection option. your cover will commence upon the date of purchase or upgrade, subject to the terms and conditions of the Promotional Period which can be found here: https://www.huaweicares.co.za/terms-conditions.html 

For Huawei Care Lite and Huawei Care Pro, your cover will commence subject to the successful receipt of your first premium.