This is how I kept track of chapters, dates, and points of view in One Summer in the Sun:
CHAPTERS and TIMELINE
before: June 4 — graduation and Hurricane Abby
JUNE
1 : Kris — June 7, Friday morning
2 : Ronnie — June 7, Friday evening
3 : Kris — June 7, Friday evening
4 : Joey — June 8, Saturday morning
5 : Ronnie — June 8, Saturday afternoon
6 : Joey — June 9, Sunday morning
7 : Kris — June 9, Sunday evening
8 : Ronnie — June 10, Monday evening/night
9 : Joey — June 10, Monday night
10 : Kris — June 11, Tuesday afternoon
11 : Joey — June 14, Friday morning
12 : Ronnie — June 15, Saturday morning
13 : Kris — June 15, Saturday evening
14 : Ronnie — June 15, Saturday night
15 : Kris — June 15, Saturday night
16 : Joey — June 16, Sunday morning
17 : Ronnie — June 17, Monday evening and June 18 Tuesday
18 : Kris — June 21, Friday morning
19 : Ronnie — June 21, Friday evening
20 : Joey — June 22, Saturday morning
21 : Kris — June 22, Saturday
22 : Joey — June 23, Sunday morning
23 : Ronnie — June 25, Tuesday morning
24 : Kris — June 28, Friday morning
25 : Joey — June 29, Saturday morning
26 : Ronnie — June 30, Sunday early morning
27 : Kris — June 30, Sunday late morning
JULY
28 : Ronnie — July 2, Tuesday morning
29 : Joey — July 4, Thursday afternoon
30 : Kris — July 4, Thursday night
31 : Joey — July 5, Friday afternoon
32 : Ronnie — July 6, Saturday morning
33 : Kris — July 8, Monday morning
34 : Ronnie — July 12, Friday afternoon
35 : Joey — July 14, Sunday morning
36 : Kris — July 14, Sunday afternoon
37 : Ronnie — July 16, Tuesday evening
38 : Joey — July 17, Wednesday early
39 : Ronnie — July 17, Wednesday morning
40 : Kris — July 17, Wednesday night
41 : Joey — July 18, Thursday afternoon
42 : Kris — July 19, Friday morning
43 : Ronnie — July 21, Sunday afternoon
44 : Joey — July 22, Monday very early
45 : Ronnie — July 23, Tuesday morning
46 : Kris — July 24, Wednesday evening
47 : Joey — July 27, Saturday morning
48 : Ronnie — July 27, Saturday afternoon
49 : Kris — July 27, Saturday evening
50 : Joey — July 31, Wednesday morning
AUGUST
51 : Kris — August 2, Friday evening
52 : Ronnie — August 3, Saturday afternoon
53 : Joey — August 7, Wednesday morning
54 : Kris — August 7, Wednesday afternoon
55 : Ronnie — August 7, Wednesday evening
56 : Joey — August 7, Wednesday night
57 : Ronnie — August 8, Thursday morning
58 : Kris — August 8, Thursday afternoon
59 : Ronnie — August 10, Saturday afternoon
60 : Joey — August 11, Sunday morning
61 : Ronnie — August 11, Sunday afternoon
62 : Kris — August 11, Sunday evening
63 : Ronnie — August 13, Tuesday morning
64 : Joey — August 14, Wednesday morning
65 : Ronnie — August 15, Thursday afternoon
66 : Kris — August 16, Friday evening
67 : Joey — August 19, Monday afternoon
68 : Ronnie — August 23, Friday afternoon
69 : Joey — August 23, Friday evening
70 : Kris — August 24, Saturday morning
71 : Joey — August 29, morning
SEPTEMBER
epilogue : Ronnie — September 2, night
All this, of course, in the summer of 1968.