Preloading: swf always shows up before 100%

Dear all,

I am loading an external swf which contains an audio file. The preloader is working well; I mean I can see the preloaded percentage and when it finished. The problem is, the swf is shown before it is 100% complete. In some way, that is ok because I do not want to load 100% of the file before to render it, but I would like to detect when the swf will be shown. It seems it always happens around 30%.
I guess this occurs because the streaming process but there is a way to control it?

Thanks in advance