A few things we've evolved over the years as we've trained sales teams for launches. Rather than leaning on broad sales trainings that include the entire sales org, we've tried smaller trainings for specific regions or teams that are tailored specifically to what is most important to them.
We've also evolved from trainings that take place a week before launch to several touchpoints leading up to a launch - ranging from trainings, to office hours, demo sessions, and on demand trainings - so sales is able to digest change over time and have plenty of time to get comfortable with selling ahead of launch.
One area that often gets overlooked, it putting the time and energy in to making sure sales has a solid demo environment and script - and feels confidently trained (and launch enablement doesn't stop with slides and a training).