"Advance warning" means being notified or alerted about something ahead of time, giving you the opportunity to prepare or take appropriate action before it happens. Full definition
Before we place any trade, we give advanced warning of what we intend to do in our updates to subscribers. (skoptionstrading.com)
But it does work, nevertheless, and proved very handy at giving advance warning of incoming enemies, or a general idea of the direction of incoming bullets from unseen enemies. (techradar.com)
They have inadequate advance warning about what they'll be teaching, so that they can adequately prepare their courses. (sciencemag.org)