How long should I wait after patching before sanding the surface (to remove paint, etc.)?

It is recommended that the QUIKRETE® Quick Setting Cement be allowed to cure for at least 2 days prior to sanding. Wear appropriate personal protective equipment when sanding. The repair area must be sound, clean, unsealed/uncoated, and free of dirt, dust, loose debris, and any other potential bond breakers. Please note that QUIKRETE® Quick Setting Cement is not intended to be used as a coating or over a large area (must be less than 2 square feet). We would recommend using QUIKRETE® Quick Setting Cement mixed with QUIKRETE® Concrete Acrylic Fortifier (No. 8610) by replacing part of the mixing water in accordance with the instructions for improved bond. When making repairs, getting a good color match can be difficult – we always recommend to trial the repair material in a small, inconspicious area first and wait 24 hours to ensure that the appearance, including color, is acceptable.