It comes down to being very clear on expectations for the rep on what they need to achieve while being transparent with the business as well. Take this path with a grain of salt, this can be cut down a bit, but this is generally what I aim to follow....
Month 1- Product/ Person Familiarity, Call/Email/prospecting tech stack certified, New hire orientation completed
Month 2- Start outbound outreach or inbound follow up, Account & territory plan proficiency, Competitive/discovery/ mini demo certs completed, Solo 1:1 with Aligned AE partners
Month 3- Day to day proficiency, Accountable to weekly activity and result metrics, Driving 1:1 conversations with Manager on planning, results and coaching
Months 4-6: Day to day expertise, persona expertise, carrying full quota, innovating new tactics, accountable to results and forecasting
Months 6-8: Full demo cert, product expertise, mentoring peers, feedback to manager on process or improvements
Month 9+: Full role expertise