That depends on what you mean by "concept to aircraft". Boeing and Lockheed Martin built flying JSF prototypes pretty quickly after receiving the initial program requirements. But it took a lot longer to reach operational status. Ironically the biggest delays were caused by software development, and that part isn't any easier for unmanned systems. Maybe Saab and Anduril will be faster than Lockheed on the software side but so far they haven't delivered anything with even a fraction of the capabilities.