Beforehand

Romans 1:2 NIV
2 the gospel he promised beforehand through his prophets in the Holy Scriptures

The promise, the good news of grace, the gospel of Jesus Christ has been fulfilled.  The words of the prophets, spoken and written, were given to pave the way for the coming Son, to explain what God was doing, and to make people ready to understand what is taking place.

In Titus 1:2 we are told this promise was made before the beginning of time.  We will only be able to understand what this means when at last we are free of time and earth, when we receive our immortal bodies and enter into the fullness of eternal life.