Hello @Tamsin9,
Yes, that's standard. For stays of fewer than 28 nights Airbnb charges the guest the full amount in advance the moment that the reservation is accepted by the host. Airbnb then pays the host a few days after the guest checks in. There may be a 30 day payment delay for new hosts.
There is a payless upfront facility offered by Airbnb in some cases. This is not something the host can specify and it's entirely at Airbnb's discretion if it's offered to the guest. In this case the guest pays 50% on booking and 50% a few days before check in.
the article below explains the charging and payout procedures.
When am I charged for a reservation?
When do I get paid?
Steve.