SCHD question

I am looking into the Dow Jones U.S equity dividend 100 index of which SCHD tracks.

One question i have is that when a stock meets the guideline to join an index and the subsequent etf tracking it, how is it bought in? Is there a methodology in which the formula decided percentage of assets is bought in or is it all at once?

I mainly have this question for Broadcom which in 2021 reached 10 years of consecutive dividends, allowing it to be added sometime in the latter half of the year, of which im trying to pinpoint the date.

I just want to see if the 36billion AUM of SCHD bought its 3%-4% of AVGO in one day last year? This order if done in a day would have been equal to the entire daily volume of AVGO around that time.