I have the same experience as Sharkbite. Also, the flash on my rifle silencers is a lot bigger on the first shot. After that, it's not too bad.
Some rifle silencers -- like the Surefire SOCOM -- are supposed to virtually eliminate this first-round flash, but I've never tested one in the dark myself. Other silencers like the SilencerCo Saker offer removable endcaps, and one of the replacement options for that can is a flash hider endcap.
Since my Saker 5.56 does have some flash, I think I'm going to get that flash hider endcap. I mainly think it looks cool, but I wouldn't buy it if it was just for looks and didn't perform any function.