Clark is set to start his first competitive match for the Gers in the League One match with East Fife at Ibrox this afternoon.
Under SPFL rules, the Third Division champions can only field two trialists in a game and each unsigned player can only feature three times.
Jon Daly and Nicky Law have been involved in the games against Brechin City, Stranraer and Airdrie United and cannot play.
Goalkeeper Cammy Bell and Clark, who banged in 40 goals for Queen of the South last season, will start the game with East Fife.
But the 22-year-old knows he has to make an immediate impact and hit the target or he will find himself out of the team once again.
He said: "I can't wait. It's been a long month just training every day and not gettign a game at the end of it. I am looking forward to getting going.
"It is hard when you are in training on a Saturday morning while the other guys are getting ready for the game. But I have got my chance now so hopefully I can do well.
"I am playing with new players so I have watched how they go about their business. It has also been good to experience the atmosphere at Ibrox.
"The team has been good. We have won all of our league games pretty comfortably so far. We suffered one upset in the League Cup, but, that apart, we have done well.
"The boys who have played have done well. It is up to me now to go in there and do well myself and hopefully get a couple of goals."
Clark added: "It is a good chance for me to show the manager what I can do. After this Saturday's game he will be able to play all eight of the new players.
"My intention is to play as well as I possibly can, hopefully score and give the manager a selction headache for the next time that we play."
McCoist has stated that he wants to strengthen his squad with another defender and another striker.
The possibility of another front man joining the Govan club is one that Clark welcomes even though it could further restrict his chances of playing in the first team.
Clark, Daly, Andy Little and Lee McCulloch are already on the books at the Glasgow giants.
Clark said: "I can only learn from training and playing with guys like Jon and Lee. I can learn from anybody with great experience.
"If somebody else comes in with that experience, somebody who has played at a higher level than I have, then I am sure it will be good for my development as a player.
"I heard that the manager had expressed an interest in bringing Kenny Miller back to the club. That isn't going to happen now apparently.
"But if it had done, or if it happens in the future, then I would relish the prospect of playing alongside a guy like that.
"Kenny has played a lot of games at a high level, including at international level, so if he was to come then I am sure I would learn a lot from him."