Nobody can answer this. If you get a normal instance, ITSM is already installed, so you have Incident mgt and Change mgt available. The duration of the implementation will rely on a lot of things we don't know, because you didn't provide them. Things to consider:
- Needed customizations to OOB to fit your processes into it
- Integrations with other systems
- Data migration
- Reporting requirements
- etc.
You can start using it on day one, because the system contains the processes already. I have seen implementations running from 3 weeks to a year, depending on the requirements.
