Impregnator 511. At HomeDepot or Amazon with a ton of reviews. I used 3 coats - use gloves and a small sponge/cloth - just wipe everywhere. Smell is strong but goes away. Copiously on bottom part of shower. Test it on a small sample to be sure there's no color change (ceramic is non-porous but best to be safe). Good advice from your contractor.

Thanks. How long did you leave it on for? Did you wipe it off with just a sponge or did u use water or something else?

Follow the manufacturer's instructions.

badabing is corrrect, as is cat, answer is you do not let 511 dry on tile surface, you wipe it dry after it soaks and then buff dry with microfiber or cotton towels. you got this, and yes whole floor

Correct above - you put it on, wait 3-5 min, then wipe the excess. Then wait 24-72 hours. I put it on, waited a day, repeated two more times, then let it dry 72 hours. I think the secret is letting the final dry a couple days at least. I used an old washcloth to wipe and slathered the floor pretty good with a smaller rag. Walls too though less aggressive.