The duration between the application of epoxy and when you will sand depends on the goal of applying it and other conditions. As a general rule, you should leave it for a minimum duration of 24 hours before sanding. In a situation where you will be shipping, it is recommended that you allow it to dry for a longer duration before you sand it.

However, if you want quick results and you want to sand it earlier than 24 hours, you can slightly increase the temperature of the location by a few degrees but make sure it is consistent. Before you begin to sand, you should inspect the epoxy to ensure that it has fulfilled the goal of applying it.

Sanding epoxy when it is dry could be a big hassle. The abrasive material could get dull quickly. To make the process easier, you can wet the abrasive material. You should do this consistently for the abrasive material until you finish sanding.