On the day of draw, whether CIC pick from whosoever available on pool that day. Or. Considers 3-4 day earlier day pool...becoz on 4th may, in cic website I think they considered whosoever on pool till 28 April. Pls let me know any insights
They will consider the instant when the draw takes place (precise time too), which is mentioned in detail in the Rounds of Invitation page.
However, they may release a breakdown of the CRS standings from a previous date. For instance, the last draw was on 4th May, but they provided a breakdown of 28th April CRS (and that's triggering your question, right?).
Updates to your profile (and scores if any) usually takes 24 hours, and hence it is always best to avoid updates to your profile during anticipated days of a draw (mostly a Wednesday).