Secondary progression
Secondary progression moves the chart forward one day for each year of life, so the sky on your thirtieth day after birth describes your thirtieth year.
The day-for-a-year equivalence is old and appears in the biblical text the tradition cites for it. In practice it makes the fast bodies useful and the slow ones nearly static: the progressed Moon covers the whole chart in about twenty-seven years, while progressed Saturn barely moves.
The two events astrologers watch for are the progressed Moon changing sign, roughly every two and a half years, and the progressed Sun changing sign, roughly once every thirty.
Frequently asked
How is a progressed chart different from a transit?
A transit is the real sky today. A progression is a symbolic chart derived from your own birth data, so it is personal rather than collective.
What does the progressed Sun changing sign mean?
It is read as a slow recolouring of identity that arrives about once every thirty years and unfolds over several of them.