I'm happy to hear you have decided to try your hand as an RMS Clerk. In my opinion, it is a great trade. Your college skills should help you quite well in the trade with respect to working in an office setting. The rest will be taught to you on your trades training, and more importantly your first posting.
When there are spots available and the CFRC calls, and you're done/passed your medical, interview, CFAT and swearing in you will get a date for which you will start Basic Training (BMQ). Check out the BMQ forum for info on that, but doesn't hurt to start running and working on your push ups if you are getting rusty.
When you have graduated BMQ you will be posted to CFB Borden. This is where you will take your course at CFSAL (Canadian Forces School of Administration and Logistics). You will likely spend sometime on PRETC, which is considered a 'holding platoon' until your trades training starts.
Once your QL3 (Qualification Level 3, this is basic trade qualification for RMS Clerks) course at CFSAL starts you will be posted to the school. When I went through the course was roughly 3 months long. You will get a great baseline education of a variety of topics that RMS Clerks do in their daily job. For example you can expect to learn:
Pay (manual and computerized), Personnel administration (leave, promotions, terms of service), Claims (there are many types of claims RMS Clerks do) as well as Central Registry. You will also become familiar with the proprietary software that allows Clerks to do their job such as CCPS (Central Computation Pay System) and Peoplesoft. During your training you will be asked to select your posting preferences. You will pick three and near the end of your course you will find out which one you actually got. Be aware you may not get posted to any of the locations you chose, rare, but it can happen.
When you have completed your QL3 you will then get your first posting, and that is when the fun begins. The trade can be very challenging, but also highly rewarding. Clerks can be employed in many facets, and there is a lot to learn. You will never know everything, but don't worry, you won't be expected to. As you become familiar with the various publications that outline policy and entitlements you will become more comfortable in your job function. Pay attention to detail (very important), ask if you have a question and try your best. I wish you the best of luck. If you have any other questions don't hesitate to ask.