Raewyn… transactions ONLY happen Mondays to Fridays. Even though branches may be open on a Saturday.
So, as your friend did it on a Saturday, the money should transfer from the Westpac account overnight on the following Monday and should (I stress should) be there on the Tuesday. Also, if a transfer happens on Friday, because the next day is Saturday nothing happens until Sunday night when it transfers to the recipient bank and customer’s bank account and shows up on, again, the Monday.
This information is available on every banks website. Suggest you actually read some of the relevant info.