God is all-knowing. To me it means that a clear, overall plan for all things is in existence always. From Scripture reading, we could safely say that God knew the plan of salvation before the world began and that he knew each one of us before we were born. I don't believe that every little thing is rigidly predetermined because God still has to deal with our free will. As we sin, rebel, repent, return to him, start praying harder...God must accommodate all these variations in his overall scheme.
We are not all-knowing, but we have the good fortune that the Lord has already revealed to us all we need to know, that is, the good news that he so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.