Not really , the LWF RFP was sent in 1972, the YF-16 prototype was rolled out in dec 1973 and first flight in early 1974.The concept , the design, realization and first flight was done within 2 years. The short development span was because of the use of mature available tech including the engine. The F-X program which later turned into the F-15 took 7 years from RFP to first flight as it involved several novelties and big govt bureaus , infact the concept of a twin engine heavy fighter dated back to the F-111 which itself was considered below the expectations.
If done sincerely , based on mature proven airframe and tech(imported and local) as it seems and excluding HAL and ADA from the process, 5 years may just be enough to develop workable prototypes provided no changes are made to the specs in between. Induction can be faster as avionics,components,ground support are already in service.