A 'month,' as in Genesis 29, signifies the end of an earlier state and the beginning of a following state, thus a new state. 'A month' signifies a full state.

(References: Arcana Coelestia 3814)

In some casual references “first” has a pretty literal meaning, as the beginning of a group; on a deeper level the “first” represents the entire group. In connection with measurements of time -- days, months, hours etc. -- it means the beginning of a new spiritual state. It is also used in connection with the Lord, who is the “first” of all existence, because everything is a product of His love. “First” is perhaps most commonly used, however, to represent what people love and desire, because what we love and desire is “first” in us, with our thoughts and intellect following. If we love people around us and desire to serve them, our ideas will follow and find ways to do it. It does not, however, work the other way around -- having ideas of how to be good won't mean anything if we lack the desire to be good. Our loves, then, contain the key elements of all that we are.