Can I use Rare Candy on a Scatterbug the first turn of the game or the turn that Scatterbug is played, since "Adaptive Evolution" says it can evolve in those cases?
No, you can't use Rare Candy to evolve in either of those conditions because the text on Rare Candy specifically prevents it.
Source: Scarlet & Violet FAQ; TPCi Rules Team (2023-03-30)

Relevant cards

Note: All applicable cards may not be listed below.
SV1_8
SV1_8
SV1_9
SV1_9
SM2_165
SWSH1_180
SWSH1_180
SV1_191