Approach for modeling the addition of salespeople

Hi everyone. I am hoping someone can suggest a simple and clean approach to the following task: creating a template that will allow the user to pick various month starts dates over a 5 year period for a variable number of newly hired telemarketing salespeople.

The hires can occur in an month of the year and there can be up to 25 in a given month. In addition, the performance of the new hires will be either poor, moderate or strong (defined as monthly revenue generated) and each will have a different 1-4 month learning curve. At the end, the model needs to calculate total monthly revenue taking into account the number of active salespeople, the performance level of each salesperson and where each is in his respective learning curve. Most imprtantly, the user need to be able to easily change the inputs for number of salespeople and thier start dates.

I suspect that vloopup/hlookup tables are the key but cannot figure out how to set them up. Any thoughts on the basic excel function or approach that can be used to construct such a template are greatly appreciated!!