I've built inbound and outbound SDR (lead generation) teams from scratch at one of the fastest growing startups in America.
Great question! My company went from 2 salespeople and no process to 50+ with solid and improving process in 3 years. Here are some lessons we learned that might help you.
1. If you don't have a built-out sales process, script, best practices, pre-written objection answers, etc, but need to move fast on hires: hire a couple people who are likely to figure it out. You can then document all of this process off of what they do well, which will help you iterate and improve over time. You can see my post about how to hire for this person here: https://www.derekjankowski.com/characteristics-of-successful-salespeople/
2. If you DO have this process put together, then you should invest in training. It might be a tough sell to management, but you should spend significant time training salespeople before you let them talk to a customer. You don't want them to practice with money (imagine playing poker with real money before you really understand how to play!). 4-6 weeks of training is not unreasonable, but it's hard to say what makes sense without more details of your situation.
3. As others have said, you mus start with your plan and work backwards. How much revenue do you need to drive? How do leads currently convert as they run through the funnel? One problem you're likely to run into: management might build a model that expects your new reps to deliver the kind of performance you have been. You actually want to cushion this number. People quit, go on PTO, or fail to learn as fast as your model calls for--the list of points of failure is infinite. Create a plan that lets you deliver 30% more revenue than management needs you to and you are likely to hit the number they need.
I've done all of these things, so let me know if you want help either flushing out the details or walking through the plan.