Avoid delay in loading time when loading large external swfs into main swf

Question

I have numerous large swfs that I am placing into a main swf using different buttons. I am experiencing quite a delay when the external swfs are called to load and play (because of their size). (Note: I do not experience any delay in loading the external swfs when playing the main swf locally, however when burned to a CD, the large external swfs load very slowly into the main swf each time their button is clicked.) The code I use to load the swfs:

var Lesson1_Loader:Loader;
Lesson1_Loader = new Loader();

Lesson1Numberbtn.addEventListener(MouseEvent.CLICK, playL1);
function playL1(e:Event):void
{
Lesson1_Loader.load(new URLRequest("Lesson1.swf"));
addChild(Lesson1_Loader);
 }

My question: Is there a way to have the external swfs start loading themselves (but not playing) when the main swf is opened (there is an introductory animation in the main swf before any external swfs are played), so that when I click each button and addChild for each external swf, it is already loaded and will play instantly without delay?

Thank you in advance!

Update: I am using timeline code (I know not preferred). I've tried to this version:

var Lesson1_Loader:Loader;
Lesson1_Loader = new Loader();
Lesson1_Loader.load(new URLRequest("Lesson1.swf"));

Lesson1Numberbtn.addEventListener(MouseEvent.CLICK, playL1);
function playL1(e:Event):void
{
addChild(Lesson1_Loader);
 }

...however then Lesson1.swf seems to play (behind the scenes) automatically at the start of main.swf (I know this because Lesson1.swf has sound on frame 1 and I hear it, however Lesson1.swf visually does not show up until I click the 'Lesson1Numberbtn' button and addChild. Lesson1.swf itself does not have "stop();" on Frame 1, so that it plays automatically when loaded. I could add stop(); to frame 1 of Lesson1.swf, but then how do I start Lesson1.swf to play from the main.swf once I addChild?

Update Again: I have tried this code to control the playing and stopping of Lesson1.swf, but it does not work:

Lesson1_Loader.load(new URLRequest("Lesson1.swf"));
Lesson1_Loader.contentLoaderInfo.addEventListener(Event.INIT, NotYetL1 );

function NotYetL1(initEvent:Event ):void{
MovieClip(initEvent.currentTarget.content).stop();
}