Environment Variables

I am trying to set certain environment variables on a Windows 2012 R2 Remote Session Host based on the client machine. I have configured a login script to set the variable, and it does work, but not when set a a login script.

Here is the vb script:

Set objShell = CreateObject("WScript.Shell")
Set objEnv = objShell.Environment("USER")
client=objShell.ExpandEnvironmentStrings("%ClientName%")

Select Case client
Case "Workstation1"
	objEnv("Variable") = "Variable Data1"
Case "Workstation2"
	objEnv("Variable") = "Variable Data2"
End Select

If I run this script, the variable gets set correctly. But if it is set as a logon script, it is not retrieving the client name. I assume this is due to the fact that the terminal session hasn't fully initialized when the script is executed.

I have made sure that 'Run logon scripts synchronously' is disabled and even set a delay in the script, but it still won't work.

Any suggestions would be appreciated.