How long does it take for the machine to be ready for use after first turning it on?
For a machine like the Rocket Appartamento or any other similar prosumer grade machine you generally want to leave the machine on for 25 to 30 minutes to stabilize the temperature. You can use it earlier than that but you're going to get the best results at around 25 to 30 minutes and for optimal temperature it's going to be at around 40 minutes. There is a lot of metal in an espresso machine like the Rocket Appartamento as it's very well built and you want all of that metal to be at a consistent temperature prior to pulling your shot. You don't want to have fluctuation in the temperature - if it's too cold you're going to get sourness in your shot and if it's too hot you're going to get bitterness. So you want a nice steady temperature prior to pulling your shots.