10% and 60 days depending how far in advance you book:
The below is copied direct from DLP's Booking T & CsFOR PHONE BOOKINGS:
4.1.1 Deposit
A non-refundable deposit of ten per cent (10%) of the total cost of your booking
will be required for bookings made more than sixty (60) days before your arrival
date (or, where transportation is included in your booking, your departure date).
This deposit is payable at the time of booking but will only be debited after your
booking is confirmed. In cases where we are unable to confirm your booking as
provided for in article 2.1, no deposit will be taken out from your card. This deposit
may exceed 10% of the total cost of your booking when including insurance or
transportation by flights (depending on terms of airline provider).
4.1.2 Balance
The remaining balance of the total cost of your booking must be paid in full no later than
sixty (60) days before your arrival date (or, where transportation is included in your
booking, your departure date). The same credit or debit card will be used to debit
balance at 60 days prior to your arrival date (or, where transportation is included in your
booking, your departure date) unless you advise us otherwise at least 65 days prior to
your arrival date (or, where transportation is included in your booking, your departure
date). If you are paying by UK Maestro, you are required to call back no later than sixty
(60) days before your arrival date (or, where transportation is included in your booking,
your departure date) for us to debit the balance.
4.1.3 For bookings made sixty (60) days or less before your arrival date (or, where
transportation is included in your booking, your departure date) the total cost of your
booking is due immediately on booking.