Bookings arrive on the POS with pre-ordered dishes and deposits already attached, so nothing is re-keyed on the day.
When a guest pre-orders dishes or pays a deposit at the time of booking, that information is waiting for you at the till. Seat the party and their pre-orders, notes and allergies come across with the booking, and the deposit is already on record. Nothing to re-key, nothing to look up on a separate system, and no awkward questions about what was agreed.