I found that when call center agents take calls sooner (rather than waiting two or three weeks to begin their work), they are able to learn the job faster. If your environment is set up with a call tree or a way to triage work (instead of a big queue), then this onboard training schedule will work perfectly.
The entry level procedure is low risk, highly repetitive. It gets them use to taking calls and documenting the calls and lets them be familiar with the environment.
The intermediate level requires a skill set of searching to find an answer and may require dispatch of an escalation to another group. By now, they know how to answer a call, and document it – now they have to search for answers.
The advanced level requires advanced troubleshooting when knowledge articles my not always be found. Expect the unexpected. By know they know how to search the knowledge base and will be able to determine not spend a lot of the time in the knowledge base and do troubleshooting instead.
Using Dick & Carey for instruction design, you can understand the pre-reqs, and competencies. This will also help you to understand the length of time it will take to be competent in a skill too.