P.S. Everything needs to be discussed and negotiated at first. The below mentioned default terms are placed to ensure such discussion takes place before the project is awarded by you.
In pursuance to "Milestone Payments" as in Freelancer.com terms and conditions, the first milestone payment needs to be deposited on Freelancer.com within a day, ibapi is awarded the project, failing which the awarding of such project by you, the buyer, will be considered void and the bid offer by ibapi will be deemed to have been retracted.
The first milestone becomes payable after requirement analysis is done. Requirement analysis is 'Contract-style requirement lists' as defined under the article 'Requirements_analysis' in English Wikipedia.
Simplified:
This is essentially an upfront payment.
The first milestone is deposited before the project is accepted by the service provider ibapi and paid after requirement analysis is illustrated by ibapi in the Freelancer.com message board.
Looking forward to hear from you.