"To everything there is a season" is from Ecclesiastes, not Proverbs.
The film takes place in May 1955. When the parishioners are coming to church late in the second part, they arrive to Albinoni's Adagio even though this wasn't published until 1958.
Although the film takes place in May 1955, Mrs. Lestrange is reading the February 1, 1956 issue of "The Tatler".