The later in the year they will debut
then they will be eligible to win rookie awards in more award ceremonies next year
just look at popular girl group debut dates for example:
IZ*ONE - 29th Oct
STAYC - 12th Nov
aespa - 17th Nov
IVE - 1st Dec
with those debut dates it's kind of like 'half year' situation
either companies debut groups in may/june (Idle, Le Sserafim) or they debut them much later in the year when 'window' for next year award show nominations opens
it doesn't really matter if line-up changed or not, because they didn't even filmed MV yet