you should be fine, its not like there going to start you off on a complicated form. it depends on who teaches it and what day you just happen to train. in the classes i go to an average day of training would be an average day of intense training, if there is a test coming up then there will be a large amount of focus towards students who are testing, and theirs other factors that can change what happens in class too
bottom line though just remain confident(teachers like confident students), calm(it helps a lot if your calm, if your not take deep breaths), and tough(whether you get tired or sore push on and be strong) there's not a single martial artist who hasn't struggled(if martial arts was easy then getting a black belt would not have as much significant meaning)
looking forward to hearing of success, best of luck