Generate a full, in-depth guide to employee onboarding. The guide must be a structured checklist. It should be broken down into: 1. Before Day One: A checklist of pre-arrival tasks (tech setup, welcome email). 2. The First Week: A detailed plan for introductions, training, and setting expectations. 3. The First 30 Days: A guide to setting initial goals and regular check-ins. 4. The First 90 Days: A framework for a formal review and future goal setting. Please include a disclaimer about adapting the plan to the specific role.