What are your payment models?
We work either for fixed-price projects, or on per-hour rates basis. For long-term committed clients who prefer time-based billing, we also offer a monthly rate.
For fixed-price projects:
Advance: 20%
Early proof-of-concept: 20%
Beta release: 30%
Final release: 30%
For per-hour rate projects:
Fortnightly/monthly
These are typical distributions and individual projects may differ in details.