Standard time for LED light testing
There are various standards depending on whether you are talking about a complete luminaire, a LED module or a retrofit lamp replacement. For example, you might need to look at IEC 62722-2-1:2014 Luminaire performance - Part 2-1: Particular requirements for LED luminaires and IEC 62717 LED modules for general lighting - Performance requirements

I found this information in this helpful document by SIRIM QAS International and by IEC searches. Another route is to find the standards that are listed in technical information documents of reputable brand manufacturers.