The developmental and evaluation phases are mutually exclusive (note: the evaluation phase is neither the test flight phase nor IOC). Test-flight involves the gradual evolution and improvement of the design/subsystems, usually at a civilian airfield, and is the phase in which actual design work is being carried out.
Evaluation is usually done after the aircraft configuration has settled (usually at the behest of the potential customer), and during which the final form of the aircraft is operated as if it were in active service; this is done to iron out any last-minute problems with either the inherent design (forcing CAC to make changes) or an individual airframe. This also allows the customer to assess the aircraft's collective capabilities during operational circumstances (which could not always be faithfully replicated during non-military testing).
It is important to note that, during evaluation, the aircraft is not actually in service, but merely subjected to the circumstances it will face as if it were operational. A successful evaluation paves the way for subsequent orders and induction of the said aircraft.
All aerospace products (including every individual airframe built by Boeing/Airbus/Embraer/etc.) goes through an evaluation phase, irregardless of when each aircraft type was "developed".
