SCP has a chart in front that tells you where we “are” the Monday after Pentecost (which week) because that does get confusing.
definitely read the preface and intor, and pp13 and following that give the outline for each hour, and read the first couple of pages of each hour with all the red instructions.
I strongly recommend before spending money on CP 1 vol or LOTH 4 vol you use SPP for at least one full liturgical year to get used to the rhythm of the 4 week psalter and the structure of the various hours. when you feel comfortable, go to the Sunday propers in the back, when you get used to the Sunday differences, start with the propers for the seasons, and major feasts. hymns are not mandatory so don’t worry about the right one, if you want sing or recite one that in general fits in with the time of day and the season.