If you're waiting for a jam and you textured a skin or created a blog,texture pack,mod,map... don't publish it, save the draft and wait until the jam starts, for example i wanted to use a Roboman skin: https://www.planetminecraft.com/skin/roboman-5940383/ (I know it isn't shaded, it's of the time i don't know shading). But the skin was old and the jam started after publishing. If the jam starts after publishing you can't post the published content.