I've only done a "partial" drain of the trans fluid, never a torque converter drain.
Will the trans accept a full fluid fill after a torque converter drain, or will the engine need to be started (at some point) to get fluid pumping into the torque converter?

Will the trans accept a full fluid fill after a torque converter drain, or will the engine need to be started (at some point) to get fluid pumping into the torque converter?