How much revenue does each customer cohort generate over time?

WITH customer_cohorts AS (
  SELECT
    customer_id,
    DATE_TRUNC('month', signup_date)::date AS cohort_month
  FROM customers
),
cohort_revenue AS (
  SELECT
    cc.cohort_month,
    EXTRACT(YEAR FROM AGE(DATE_TRUNC('month', o.order_date), cc.cohort_month)) * 12
      + EXTRACT(MONTH FROM AGE(DATE_TRUNC('month', o.order_date), cc.cohort_month))
                                      AS month_number,
    SUM(o.total_amount)              AS revenue
  FROM orders o
  JOIN customer_cohorts cc USING (customer_id)
  WHERE o.status NOT IN ('cancelled', 'refunded')
  GROUP BY cc.cohort_month, month_number
)
SELECT
  TO_CHAR(cohort_month, 'YYYY-MM')   AS cohort,
  month_number,
  ROUND(revenue::numeric, 2)        AS monthly_revenue,
  ROUND(SUM(revenue) OVER (
    PARTITION BY cohort_month
    ORDER BY month_number
  )::numeric, 2)                     AS cumulative_revenue
FROM cohort_revenue
WHERE month_number BETWEEN 0 AND 5
  AND cohort_month >= NOW() - INTERVAL '12 months'
ORDER BY cohort_month, month_number