Typically the schedule will exist in a scheduling tool such as Microsoft Project. Using the WBS as a model, create the schedule and enter dependencies and resources. At this stage resources may be role based such as BA1 or BA2 (Business Analysts 1 and 2). If resources have been allocated to the project, by all means enter their name.
The duration will be dependant on the number of resources and the time they are allocated to the project. You will probably have some idea of likely allocation so use that availability to structure the plan. If you are working to a fixed deadline, obviously you need to adjust resources to fit. If you are short on resource allocation, utilise known resources and create a role without an allocated person to fill the remaining work.
The goal of this activity is to say
"With this number of resources, the project can be completed by such a date."
It sets the stage for negotiation around changing the mix of available resources, scope and completion date.