I would argue that statement. While yes, some epoxies available to the general public can withstand about 3 pounds moisture vapor emissions (MVE), moisture blocking primer epoxies can withstand as much up to 20 pounds of MVE. Which is why they make great base coats. The adhesion to concrete...
Diamond grinding is the preferred method of prepping concrete floors for coatings. Acid etching is old school and not really as effective.
Just don't get your floor all dirty and you can really apply your coating anytime but why would you want to wait? Metallic coatings look pretty cool if...