Open the application on the desktop you wish it to open on. Right click the top bar and choose Advanced --> Special Application Settings. There you can set the size of the opening window, which desktop it should open on and other items. Advanced --> Special Window Settings is similar.
My Skype settings look like this;...
Talking about PCLOS KDE last version.
The application is
linuxdc++. I set it to autostart and it does it at every account on the first virtual desktop.
For me it isn't a pain but for my
moms account it would be better it to start in some other desktop otherwise she finds herself in trouble; she needs only internet browser which I set to autostart too.
Now following your directions I opened linuxdc++ in fourth virtual desktop and right-clicked on the top bar of its window (can't do a "Print Screen" of this). There's no "Advanced --> Special Application Settings" but the usual "Minimize/Maximize/.../.../Move to workspace" etc.
I think I don't understand something?