You can dramatically improve the quality of the first cup of coffee out of the machine each time the machine has been idle by simply pushing the flush button
The flush cycle causes the brewing thermoblock (there is a separate thermoblock in DeLonghi machines for the steam wand) to heat up and water is then heated and pumped through the group. This gets all the components in the brew path up to the correct temperature, and also serves to warm up your cup too
Simply tip the water out of your cup after the brew cycle completes, give it a quick dry, then push the button for your espresso
You will find that that taking the time to run the flush cycle dramatically improves the taste of your espresso
Obviously this is not necessary for the second, third, etc espresso as the machine is now up to temperature