Is there a way to detect as soon as a dialoug window opens with vbs

Is there a way to tell exactly when this program is open rather than sleep and hope it's open?

Dim WshShell, ret
Set WshShell = Wscript.CreateObject("WScript.Shell")
WshShell.Run "uninstall.exe"
Wscript.Sleep 20000
ret = WshShell.AppActivate("Program")
If ret = False then
 Msgbox "Uninstall Failed Error Code: 0"
 Wscript.Quit
End If
 WshShell.SendKeys "{ENTER}"

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