Here's how to use an anti-yellowing shampoo after bleaching:

1. Wait for 24-48 Hours: After bleaching, it's recommended to wait at least 24 to 48 hours before using an anti-yellowing shampoo. This allows your hair to settle and the cuticles to close slightly, which can help the toning process be more effective.
2. Clarify First: If your hair has product buildup or residue from the bleach, start by using a clarifying shampoo to remove any impurities that could interfere with the toning action of the anti-yellowing shampoo.
3. Wet Your Hair: Thoroughly wet your hair under warm (not hot) water. Hot water can open the hair cuticle too much, which can cause the toning pigments to fade quickly.
4. Apply Anti-Yellowing Shampoo: Take a quarter-sized amount of the shampoo (or more, depending on the length and thickness of your hair). Focus on applying the shampoo to the parts of your hair that have yellow or brassy tones, which are often the mid-lengths to ends.
5. Massage and Leave-In: Massage the shampoo gently into your hair and scalp. Some anti-yellowing shampoos may require a longer dwell time (usually mentioned in the instructions). This is to allow the violet or blue pigments to work effectively against the yellow tones.
6. Rinse Carefully: Use cool or lukewarm water to rinse the shampoo out. Cold water helps seal the cuticle, locking in the toning effect.
7. Conditioning: Follow up with a conditioner that complements the shampoo or a purple-tinted conditioner. This helps to hydrate and maintain the health of your hair, which is especially important after bleaching.
8. Frequency: You don't need to use an anti-yellowing shampoo with every wash. Start by using it once or twice a week and adjust based on the results and the condition of your hair. Overuse can lead to dryness or an unwanted purple cast.

Always refer to the specific instructions provided by the manufacturer of the anti-yellowing shampoo you are using for the best results and to avoid any adverse effects.