I understand, i'm not here to contradict what he says, because technically it is probably the safest option.
But in reality, IRCC are well aware their system counts work experience by month and not days, and that many people will be in this situation were they are invited and will receive ITAs before they technically have 3 years of experience.
I've not known anyone to get a rejection because of that. My good friend just had this very situation and waited for the days to elapse post-ITA, submitted his application, and got his PPR.
IRCC will not penalise you based on how their system functions.