Personally, I traded on my mules right away (given, they did have membership and used that time to cooldown too) but that's just me personally everyone else could be a bit different
I always use junk no matter how big or small the trade is, even if it's just say a few runes, or the start kit you get straight off tutorial island etc, no matter the junk it just flags a bit less. You could also in such cases say a t-bow, try instead of low tier stuff maybe rune/dragon items instead, that way bulking the trade out a bit easier, so less likely to be connected to RWT and more a trust trade/accidental trade
my new mules (I made them just before halloween ish, got hit just after halloween) all got trained but 2, somehow even the last 2 t hat didn't have anything going on got hit as well so seemed like a chainban from them, and I lost a LOT of gold lol but hey it's all learning from mistakes, good luck