There's a lot of nonsense in this thread about calibration. People are talking like they're multimeters or something.
If there's any pieces of paper in the box then it's a calibration "report", not a calibration "certificate".
These things are
not certified (or even certifiable!), you're supposed to press the 'calibrate' button
every time you want an in-spec reading.
My copy of the Rigol manual says:
"The self-calibration program can quickly make the oscilloscope reach the best working state to get the most precise measurement values. You can perform self-calibration at any time especially when the change of the environment temperature is up to or more than 5 degrees C"
At a minimum you probably need to do it once in summer and once in winter to compensate for average temperatures. You might even need to do it morning and afternoon, depending on how the sun hits your workshop.
Then again: Relax. They're only 5% accurate even after recent calibration so what the heck?
Forget about the 'calibrate' button and just use it for what it's supposed to be used for, ie. looking at the shape of wiggly lines on a screen with
approximate indication of voltage. You want to measure voltages accurately? Use a multimeter.