Chapter IV covers sections 204-252 and instructs us on Various Celebrations Throughout the Year.
Sunday is given first treatment:
204. The office of Sunday begins with evening prayer I, which is taken entirely from the four-week psalter, except those parts that are marked as proper.
205. When a feast of the Lord is celebrated on Sunday, it has a proper evening prayer I.
206. The way to celebrate Sunday vigils, as circumstances suggest, has been discussed in GILH 73.
207. It is of great advantage to celebrate, when possible, at least evening prayer with the people, in keeping with a very ancient tradition. [See SC 100.]
Sunday begins with the first Vespers, the prayer offered on Saturday evening. Either evening prayer I or II would be the first priority, other things being equal, for implementation in a parish not praying the LH publicly.