In my experience, advisors do not fail due to lack of technical or product knowledge. They fail because they are unable to market themselves and attract a sufficient number of clients. While putting your new advisors through the CFP designation is valuable (I am one myself!), it does not fully prepare a new advisor for the challenges they will face early in their business development.
My advice would be to focus instead on allowing new financial advisors to shadow seasoned advisors and to focus your training on prospecting and sales skills.
You learn best by doing, and shadowing seasoned advisors can be the best way to prepare for the day-to-day challenges and demands of the profession. For example, you will learn how to prepare for, conduct and follow up after a client meeting. These real-life scenarios will accelerate your learning. Consider handing off smaller clients to new advisors for servicing and additional sales opportunities.
Consider focusing your training on prospecting and sales skills. Either create your own selling system or enroll new advisors in a sales course (I learned the Sandler Selling System, but there are many others available). It is critical that they learn sales skills, including telephone skills like how to get past the gatekeeper, speak succinctly and with high impact, overcome objections and close for appointments.