Cokanasiga shone in England's 57-14 win over Italy in round four, but was surprisingly omitted from Sunday's (AEDT) Calcutta Cup clash at Twickenham in favour of Jack Nowell.
Jones is keen to use the experience of Nowell and Ben Te'o against Scotland, with England still in with a chance of snatching the title out of Wales' hands.
Cokanasiga is not out of the picture, though, with Jones expecting the 21-year-old to play a crucial role when England travel to Japan later this year.
"He's a good young player and we're looking after him," Jones told a media conference.
"He's going to feature very strongly in our plans for the future but we just feel this week that Jack Nowell is our best player in that position, and we feel Ben Te'o can do some good work for us off the bench, so Joe becomes our 24th man.
"He's a young player and we don't need to rush him, we need to bring him through carefully, he's got a long career ahead of him.
"We've got a plan in place for him, a good plan in place for him, he'll be ready by the World Cup. I don't need to reveal my selection plans for the future, but I do know that we'll have him ready for the World Cup.
Jones said: "He's a young player and you need to bring young players through carefully.
"I've had reasonable experience in doing this and sometimes you let them go, and sometimes you've got pull them back a bit.
"We just feel it's right for him not be involved in matchday squad but he'll still learn from being around the squad. And he'll feature heavily in our warm-up games for the World Cup."