Will enacting instrumentality lead to attaining nimitta-bhava as described by Krishna?

According to Osho, yes. Begin by acting as a mere instrument; this conscious enactment cracks the ego’s forgetfulness, like Rama remembering himself in Ramlila. Because you already are a conduit of existence, sustained acting becomes remembrance: doing shifts to being, and nimitta-bhava flowers. The Divine functions through your hands and feet; practicing instrumentality simply uncovers this timeless fact.