Wales-qualified centre Sage joined the Dragons last November with Jackman keen to get him in the environment as soon as possible.
The 23-year-old impressed last weekend as a second half replacement for the injured Jack Dixon.
And Jackman revealed the Cape-Town born back could now start against Glasgow Warriors at Scotstoun Stadium on Saturday.
“Jarryd has been good for us off the bench and he deserved a crack,” said Jackman. “He was good for us in pre-season and has got himself in really good shape.
“He looks sharp with ball in hand, has good footwork and he is good in the contact area. Jarryd could come in and deserves it.
“We knew Sagey wouldn’t be the finished product until now,” he added. “We got him in early last season to cover injuries, but you can see now he is much more comfortable with this environment and we’re excited by him.
“He is a young player with a lot of potential and it does take time to adjust.
“Up until now he has played most of his career in Johannesburg with a little stint with the Kings. He is definitely much more comfortable now."
Dragons return to action at Rodney Parade against Cardiff Blues on Saturday 6 October, 5.15pm. Early bird tickets are available until midnight Friday.
CLICK HERE to secure your tickets for the game.
