preconceptionally

The story

1. Proto-Indo-European*per-
2. Proto-Indo-European*preh₂-
3. Proto-Indo-European*préh₂i?
4. Proto-Italic*prai
5. Proto-Italic*prai-
6. Latinprae-
7. Middle Englishpre-
8. Englishpre-
9. Proto-Indo-European*ḱe?
10. Proto-Indo-European*ḱóm
11. Proto-Italic*kom
12. Proto-Italic*kom-
13. Latincon-
14. Proto-Indo-European*kap-
15. Proto-Indo-European*kapyéti
16. Proto-Italic*kapjō
17. Latincapiō
18. Ancient Greekσῠλλᾰμβᾰ́νω (sŭllămbắnō)
19. Latinconcipiō
20. Latinconceptiō
21. Old Frenchconception
22. Middle Englishconcepcioun
23. Englishconception
24. Proto-Indo-European*h₂el-
25. Proto-Indo-European*h₂élisder.?
26. Englishconceptional
27. Englishpreconceptional
28. Proto-Indo-European*leyg-
29. Proto-Germanic*līką
30. English todaypreconceptionally

From preconceptional + -ly.