Need average timeline to up to Win. 2000

What would you say would be the timeline for this type of upgrade? To install and configure for Windows 2000 advanced Server and Terminal Services for Thin Clients. We presently have the following:(2)Windows NT servers and (1)Terminal Server. We will also be upgrading (19)workstations and 13 terminal stations to Windows 2000. The operating systems for the workstations are Win 95. Our servers are NT 4.0.