Semi-Technical: When to put a preloader?

Hello ever-E1.

I am not sure if there is some sort of “common practice” or even a “rule” for this but at what file-size of the final SWF do you suggest using a preloader? I mean- if it’s something small like under 40 kB, for example- would a preloader even make sense?

I’m just generally interested in what you all ended up picking as a threshold for yourself… I don’t need tips how to make one or anything ^^