18 Screens?!
Wow, thats a lot of screens...
are they design created or runtime created screens?
As agraham states, a screen only exists after 1st presentation, so I would suggest this aproach..
on fresh run, shown all forms in reverse order, thsi should only take a few ms....
By doing this you make all forms existing so they can be propertie changed...
Then when showing a form other than main form (form1 by default), re-set the position of the form you want to show....
this eliminates the "jumping" efect, and the first few ms should be almost un-noticeable....