+1 on the 4 hour idea.

Actually, if you know you'll be making some espresso in the afternoon, i would set the timer to turn it on in the morning one hour before you need it and then leave it on until you are done.

Just be sure to run a bit of hot water through the hot water tap at then end of the day to top off the boiler. This way, you won't get woken up by the autofill kicking in when it turns on! (i live in a loft, no walls between me and the machine...)