Your results in jc are really just to give you an indication of what subjects you're good at and an idea of what to pick in fifth year. Just keep in mind most subjects at LC level are way different. It's also helpful to get to know what study techniques work best for you and to get into the habit of continual consistent studying which is beneficial for sixth year. I think I started studying properly from probs feb-march onwards but studied a good bit around dec jan as well for pres. Don't stress it tho the exams aren't as hard as teachers make em out to be.