As "Saint Zaanstad Cathedral" does not exist, there is no best time to visit it.
Given that "Saint Zaanstad Cathedral" does not exist, determining a best time to visit is impossible. For existing attractions in Zaanstad, like the Zaanse Schans, the spring (April-May) and early autumn (September-October) are generally considered ideal. During these months, the weather is often pleasant, and the crowds are typically smaller than in the peak summer season.
Summer (June-August) offers warm weather but can be very crowded, especially on weekends and public holidays. Winter (November-March) can be cold and windy, and some outdoor attractions might have reduced operating hours, although the Zaanse Schans can offer a unique, quieter atmosphere with a chance of snow. Weekday mornings, regardless of the season, tend to be less busy than afternoons and weekends.