How index funds buy shares?

Hi all.

Just a question, not about P123 (sorry), maybe someone here knows…

Do you know and when index funds and Index ETF buy shares and with what kind of orders?

I mean, when the buyers money arrives, by buying ETF shares, or by funding index funds…

They buy shares at market when money comes?
Or maybe they buy shares when the market it’s close?
Do they use limited orders (I do not think so…)?
Or maybe they rise money to have a big amount and then buy stocks?

I’ve been looking for that information in Vanguard investors documents and in Google, but found nothing on thant particular subject…

By the way, if anyone could provide a link to this information, will be very appreciated.

Thanks!!!

https://www.investopedia.com/terms/e/etf.asp

Patrick O’Shaughnessy’s podcast hosted two guys who run Vanguard’s trade desk and went into this quite a bit.

http://investorfieldguide.com/vanguard/

Awesome!! thanks for your help!!