I thought the 'visible' check applied a global setting, which will be in effect from the start to the finish of an animated sequence.  To make something appear in the course of an animation, you probably need to use some tricks with scaling, translation, or animated transparency effects in the materials set up for the item in question.  Or render two or more animated sequences and composite them in some video editing software.

Scaling or translating a conformed garment might not work well, if at all, unfortunately....

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.