A content delivery service includes a management service for determining an anticipated window of time in which supplemental content can be inserted in the dynamic content stream. The management service will then pre-fetch supplemental content from the third party supplemental content service prior the identification or request for supplemental content to be included in the streaming content. During the streaming of content to individual users via an established channel, as markers for insertion opportunities are identified, the content delivery service will attempt to utilize the pool of pre-fetched supplemental content.