I wasn't sure where to post this but it mostly concerns the helmet. I was doing research in the movies on how to damage my helmet. I'm shooting for a ROTJ:SE costume. So ROTJ everything but ESB bucket. Here is the thing, there is only ONE shot in all of ROTJ SE that has the ESB bucket and that is right after Boussh/Leia comes in with Chewie, all others are original ROTJ helmets. Rather inconsistent to cuz the helmet changes back like nothing ever happened.
It turns out however that the ESB costume is not the first screen used costume. It is #2 except for the jet pack. The reason I say this is Boba is wearing a mostly ROTJ style costume in ANH:SE when Han is talking to Jabba. That scene was orginally shot in 1977 for Star Wars but was cut in post-prod making that Fett costume the first before ESB.
I've included the best shot of Boba Fett from that scene. The arrows point everything out and it's all labeled according to the movie we most attribute the styles to.
It would appear that the ROTJ helm, gauntlets, cape, ammo belt, and EE-3 were the first costume parts to ever be used for the screen (even though they weren't seen until 1997).