Short answer
Train people on their own processes using your own data in a training environment, as close to go-live as practical, and back it up with job aids and super users in each department. Role-based, hands-on training beats long classroom sessions on every module.
The training that works is built around what each person does, so an accounts payable clerk should spend their time processing invoices in a system that looks like yours, with your vendors and your approval rules, rather than sitting through a general tour of every module. I would ask the implementation partner to train a group of your own staff as trainers, because people learn better from a colleague who knows how your agency works, and it leaves you with the skills in house after the consultants leave.
Timing matters a lot, since training delivered months before go-live is mostly forgotten, so I like to schedule role-based sessions in the few weeks before launch and give people access to a practice environment where they can try things without fear of breaking anything. Short job aids with screenshots for the most common tasks tend to get more use than a thick manual, and recorded walkthroughs help with turnover later.
After go-live, plan for floor support and refresher sessions, especially around the first month-end close, the first payroll and fiscal year end, because those are the moments people need help the most. The Start at Zero Navigator covers how to plan training and support, and it is free.