With the new series releasing their 1st volume, in a matter of curiosity i checked the 1st day for the 1st volume of all releases from Shonen Jump since Shoseki started the daily rankings, including mini series too, so decided to organize in a big ranking and post to anyone interested, but something to remember, there's no context applied, is simply the ranked for best 1st day to worst, and the tied series was decided based in longevity/sales.
The ranking:
Top Best 1st Day on Shoseki
1. Boruto: Naruto Next Generations (#1)
2. Naruto Gaiden: The Seventh Hokage and the Scarlet Spring (#2)
3. My Hero Academia (#4)
4. Burn The Witch (#4)
5. The Elusive Samurai (#4)
6. Isobe Isobee Monogatari (#5)
7. Robot x Laserbeam (#6)
8. Blue Box (#8)
9. We Never Learn (#9)
10. Sesuji wo Pin! (#9)
11. Jujutsu Kaisen (#10)
12. Dr. Stone (#10)
13. Ayakashi Triangle (#10)
14. Ginga Patrol Jaco (#10)
15. Illegal Rare (#10)
16. Black Clover (#11)
17. Hinomaru Zumo (#11)
18. World Trigger (#12)
19. Yuragi-sou no Yuuna-san (#13)
20. Witch Watch (#15)
21. Cross Account (#16)
22. The Promised Neverland (#17)
23. Hungry Marie (#18)
24. Kagamigami (#19)
25. Soul Catcher(S) (#20)
26. Salmon-kun wa Summoner (#20)
27. Chainsaw Man (#21)
28. iShoujo (#21)
29. Mononofu (#24)
30. Kurokuroku (#25)
31. Gakkyu Hotei (#26)
32. Mashle (#27)
33. Ibitsu no Amalgam (#28)
34. Dr. Stone Reboot: Byakuya (#29)
35. Undead Unluck (#29)
36. Act-Age (#30)
37. Samurai 8 (#30)
38. Tomatoypoo no Lycopene (#30)
39. Ultra Battle Satelite (#30)
40. Kimetsu no Yaiba (#31)
41. Lady Justice (#35)
42. Spring Weapon Number One (#37)
43. Sakamoto Days (#38)
44. Mission: Yozakura Family (#40)
45. Magu-chan: God of Destruction (#40)
46. Takuan to Batsu no Nichijo Enma-cho (#40)
47. Noah's Notes (#43)
48. Me & Roboco (#44)
49. Poro no Ryuugakuki (#44)
50. Agravity Boys (#45)
51. Shuudan! (#46)
52. Hachi: Tokyo 23-ku (#50)
53. Mitama Security (#51)
54. The Comiq (#53)
55. Ziga (#53)
56. Candy Flurry (#54)
57. Mitsukubi Condor (#54)
58. Moriking (#58)
59. Full Drive (#58)
60. Time Paradox Ghostwriter (#60)
61. Smoky B.B. (#62)
62. Hard-Boiled Cop & Dolphin (#63)
63. Shishunki Renaissance! David-kun (#66)
64. Takujou no Ageha (#66)
65. Kaizou Ningen Roggy (#66)
66. Kamio Yui wa Kami wo Yui (#67)
67. Alice & Taiyo (#67)
68. Love Rush! (#68)
69. Hi-Fi Cluster (#71)
70. Stealth Symphony (#75)
71. Phantom Seer (#74)
72. Gokutei Higuma (#78)
73. Yoakemono (#80)
74. Koisuru Edison (#85)
75. Tokyo Shinobi Squad (#86)
76. Iron Knight (#88)
77. U19 (#90)
78. Red Sprite (#96)
79. Build King (#97)
80. Bone Collection (#100)
81. Bozebeats (#103)
82. Hime Doll!! (#105)
83. Bokura no Ketsumei (#107)
84. Jimoto Ga Japan (#110)
85. Judos (#117)
86. High School Family: Kokosei Kazoku (#118)
87. Devily Man (#124)
88. Kowloons Ball Parade (#136)
89. Momiji no Kisetsu (#136)
90. ne0;lation (#140)
91. Best Blue (#148)
92. Double Taisei (#150)
93. Saigo no Saiyuki (#150)
94. E-Robot (#151)
95. Guardian of the Witch (#157)
96. Tanaka Seiji (#160)
97. Beast Children (#161)
98. Mutou Black (#163)
99. Tokyo Wonder Boys (#172)
100. i tell c (#179)
101. Kimi wo Shinryaku Seyo! (#184)
102. Koi no Cupid (#195)
103. Buddy Strike (#201)
104. Ole Golazo (#205)
105. Golem Hearts (#211)
106. Sporting Salt (#236)
107. Zipman!! (#268)
108. Demon's Plan (#292)
Obs: In blue are the series being published.