I partially guessed and now can't reconstruct how it was supposed to be solved. I see the letters are third from last place in every themed answer except the last, but I can't see how they should have been found.
I revealed because after I saw the theme entries (not hard, given that Ricky labeled them) I had no idea. After reading these comments, I see that the title ("Start the Day Off Right") is a big clue. Each of the five entries has a common three-letter abbreviation for a day of the week (Sun, Wed, Mon, Sat, Tue) at the end, with an extra letter inserted. Those extra letters, in label order, spell out "grits".
Oh, this was awesome. Initially I was going down the path of finding scrambled breakfast items in the theme answers. HUEVOS is in chekhovsgun, as is sunchoke. TOAST is in photostat. NUTRIENTS is in internetuse. But I struggled like crazy to find ANYTHING in yellowred.
Fermion kept taking me to some combination of FE and IRON, and then in conjunction with NUTRIENTS, I started looking for periodic elements to start/finish the words... nope. Argh. Those were some very convincing rabbit holes. Walked away, sat down just now for one last look before bed... boom. Immediately got it.
Wrote down the themers in order but couldn't see the days in there. But knowing you are a fellow son of the South, I found the "grits" and then backsolved to Step 1.
Shorthand for a certain Russian playwright's belief that "one must never place a loaded rifle on the stage if it isn't going to go off. It's wrong to make promises you don't mean to keep" (1)
20A
Punjab city
22A
Perform the task expertly
23A
"Trust Exercise" novelist Susan
25A
Form's first blank
27A
Peter of reggae
28A
Pop like never before?
30A
Draw
32A
Propelled a scull
33A
Symbol of change
35A
TDs are worth six
38A
One more than due
39A
Subatomic particle class named for the 1938 physics Nobel winner (3)
41A
"Yeah, right" sound
42A
LAX listing
43A
Highway ramps, often
44A
Many a garden statuette
46A
Comedian Davidson
47A
Sway unsteadily
48A
Group whose logo looks the same in a mirror
51A
Clear the blackboard
54A
Dr. Pepper, e.g.
55A
Linger aimlessly
57A
Glides
59A
Web surfing and the like (5)
61A
Young boy
64A
Getting on in years
65A
Flutist, e.g.
66A
Imitate
67A
___ voce (quietly)
68A
Image-sharing site studies show is terrible for teenagers, to teenagers
69A
Bike / swim / run race
Verticali
1D
Letters of distress
2D
Hill worker?
3D
Color that's not quite orange but getting there (2)
4D
Engine rpm gauge
5D
Like me when reporting yet another DSL outage to AT & T, usually
6D
Former SNL cast member Cheri
7D
Compare
8D
It often starts in Sept.
9D
Prosecco alternative
10D
Where the work is taking place
11D
Non-Hispanic white person, in slang
12D
1938 victor over Schmeling (this year's two appearances in this puzzle's clues being merely an interesting coincidence)
13D
Electropop instrument
19D
Running by itself, as a machine
21D
Helper
23D
Big bill
24D
Crux
26D
Comedian Tracee ___ Ross
29D
Charge for a spot
31D
Appalachians, e.g.
33D
More in need of rain
34D
CPR expert
35D
Early document copier (4)
36D
Under control
37D
She teams up with the Princesses of Power
40D
Short-termer shadowing a professional
45D
Bird abode
46D
Obvious
47D
China shop ensemble
48D
Assumed name
49D
Drum beaten by beatniks
50D
Went defunct, in slang
52D
Be part of the cast of
53D
Courses in bowls
56D
Thus
58D
"Will be," in Spanish
60D
Prefix with center or genetics
62D
National Poetry Mo.
63D
Innocuous set of multicultural initiatives currently serving as a right-wing dog whistle (abbr.)