IME often it updates in the middle of the night during a weekend, as well as when your statement closes and (it seems to me) when you pay the bill. It's at irregular intervals and I haven't been able to figure out the minimum lag between a big charge posting and an update.

Remember that charges posted in the calendar year count; the transaction date doesn't matter. Also fees (including the card's annual fee), interest, money-like transactions, and returns/credits are excluded.