The onboarding process can be sped up for a guided onboarding if you are able to get through the work quickly, allowing you to focus on other aspects. For a managed onboarding, the process can be sped up within reason.
With a guided onboarding process, as the implementation is done by you, the faster you get through the work, the faster you can start to focus on the other aspect of onboarding. Working with a partner will allow for more flexibility, although with a managed onboarding, the process can only be sped up within reason and at the capacity of your onboarding team.