Jesus did not say. This is what the GB say.W 13 7/15
12 When did Jesus appoint the faithful slave over his domestics? To answer that, we need to go back to 1914—the beginning of the harvest season. As we learned earlier, at that time many groups claimed to be Christian. From which group would Jesus select and appoint the faithful slave? That question was answered after he and his Father came and inspected the temple, or spiritual arrangement for worship, from 1914 to the early part of 1919.* (Mal. 3:1) They were pleased with a small band of loyal Bible Students who showed that their heart was with Jehovah and his Word. Of course, they needed some cleansing, but they humbly responded during a brief period of testing and refining. (Mal. 3:2-4) Those faithful Bible Students were true Christian wheat. In 1919, a time of spiritual revival, Jesus selected capable anointed brothers from among them to be the faithful and discreet slave and appointed them over his domestics."
They claim that he selected capable anointed brothers from amongst a small band of loyal bible students. Their answer is very unclear but they were male and it was only a small number, more than one person.
It is a good question to ask any JW, they will not be able to answer it without being just as obscure. If they cannot be identified then there cannot be any basis for them claiming that they know who was appointed as the fds, or that they actually were.