Fining means adding whatever clearing agent you will be using, such as gelatin, Irish moss, Polyclar, or isinglass. So basically, Jim C is saying to go ahead and add the clearing agent as soon as fermentation has finished, instead of letting the yeast and other 'clumpables' float around in the brew for too long. This will probably result in a cleaner flavour, as well as a nicer-looking beverage.