Tub & Tile Refinishing Kit

Submitted to Product Chat

I heard on a YouTube video I should prime the black tile prior to using the refinishing kit to avoid having to do more than 2 coats of refinisher. Is this true? If yes, what type of primer should I use? I also want to get rid of doors and add a shower curtain. Any recommendations to fill the screw holes in tile prior to refinishing? Thanks!