Spiritually, "beginning" happens when we first start new growth -- new levels of awareness and willingness to receive goods and truths from the Lord, and use them. In the Word, "beginning" doesn't just mean the beginning of something in time. In the inner sense, it means the initial phase of a spiritual state.

To be fruitful relates to goodnesses, and to be multiplied, truths.

(References: Arcana Coelestia 1014, 1018)