I keep mine on 24/7.
I put the NAD components into "standby" and the Plinius just stays on (per Plinius' recommendation and my listening pleasure). If I turn off the NAD stuff completely for a couple of days, they warm up in a few hours. However, the Plinius takes a frikkin' week! I'll never turn it off, unless I absolutely must (e.g., storm)!