The 'bookedSince' query can be used to request all booking contracts after a given date. You can use this query recursively to schedule periodic requests. Consider the case of a request made at time T1. If you want to make a request for contracts for all capacity booked since that time, you can use the query, 'bookedSince T1.' This new request will have been made at time T2. You can then use the query 'bookedSince T2' to get all bookings since T2. Repeat this process recursively to make periodic requests.
For more detailed information about the possible queries, see the developer documentation.