Your right to an extant, it use to be three years service from your 18th Bday (if you joined before 1, however the criteria changed in Sept 06 and now for a 'tradesman' LCpl all you need is your Class 2 (you normally get it approx. 6 months after arriving in your first unit) and an Annual Report with a reccommendation for promotion. You will then have to go and complete JCLM 1a (although its changing into a Cadre course which is gonna be four days tactics/four days theory course), which is a week long course teaching you want you need to know as a JNCO.
Well done for asking, promotion is not a right it is something you have to work for, you need to be better at your job than those of your peer group, you need to be aware of what is going on aground you and you need to be a very good soldier. The best advice is, keep it shut, keep your eyes open, soak it up like a sponge and always be in the top three of what ever you do. If you follow these simple rules you should do well. Dont worry about your spelling there will always be some smart arse who will correct it for you