Wales fly-half Jones has been ruled out of action for at least four weeks after straining medial knee ligaments in the Scarlets' European victory over Benetton Treviso last weekend.
Priestland slotted in at outside-half in that triumph and hopes he can continue to shine in Jones' absence with crunch Magners League derbies with the Ospreys and Newport Gwent Dragons on the horizon.
"I don't want Steve to be injured but if it's an opportunity for me I have to take it," said Priestland.
"It's never good when one of our best players is injured especially over such an important period.
"Christmas is always a busy period in Welsh rugby and if you are playing well for your region you are going to be there or thereabouts for Wales.
"When you are playing against fellow Welsh regions you are playing against guys who have either got the national shirt or are close to it.
"But ideally I would just like to concentrate on what is happening down at the Scarlets. My main priority is to try and get as many victories as we can.
"We have momentum and are in a good position in the Magners League and the Heineken Cup."
Priestland revealed he is happy with his development and form but admits he still has a lot to learn.
"I've played quite a lot this season and am quite comfortable with the way I have performed," added the 23-year-old.
"I am probably playing the best rugby of my career with the Scarlets at the moment. I always prefer to play 10, but when Stephen is down here, it is not always going to happen.
"I was not too keen on playing at full-back a while back. But I soon learned the lesson that it is better to play at 15 rather than be on the bench for a month. I know there are things I have to work on as a 10."
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland