If you've received the Animal Letter Sound Cards as part of the Reading Subscription, they are split up between two deliveries. You'll receive the first 12 cards and the matching box in Box 2 of Part 1: Sounds to Reading. You can expect to receive the remaining 14 cards in Box 3 of Part 1: Sounds to Reading.
If you have purchased the Reading Skill Set Part 1 outside of the subscription, you'll receive the full set of 26 cards at once.