The leaving thing is so hard! I've managed to go out a couple of times for 20-30 minutes (never food-shopped so fast in my life!), and I too waited outside the door for a minute to hear if he was barking - thankfully not, I think. Otherwise, I've left him in his crate and gone and watched TV in another room for an hour, but that's when he's sleeping anyway, so doesn't really count! We try to put him in his crate a few times a day. If he barks I sit near the cage and say "shhhhhh" and "it's okay" in a reassuring voice and eventually he settles down, making cute-but-pathetic grumbly noises. "I don't really want to lie down mummy but I guess I will, since you're there," he seems to be saying. I then creep away when his eyes are shut!
The first week if we did it sometimes he'd just bark his head off. Once the neighbour knocked on the very thick brick wall I realised that I couldn't crate him when he was really excited, so now I'm careful about when I do it. After meals seems to work (if he's been out already). Or after frenetic playing times.
I must make more effort to leave him for longer periods. Our last dogs could go a good few hours without worrying, although I don't really remember what they were like as puppies. The crate training does seem to make things harder sometimes, but I'm persevering with it as I'm sure it'll work eventually (and I'd rather he ate his bars and his toys than my furniture!).
I'm sure it'll get better with Luca, just persevere - small steps! For me it does seem to be getting gradually better (although last time I made a comment like that he woke me about 4 times during the night!); he's now 12 weeks. He's having his first night away tomorrow (at my mum's as we're going to the Olympics - yay!) so that'll be an interesting experience. I've ordered an identical crate for him, so hopefully it won't feel too alien, and I'll take his toys. I'm also going back to sleep there, so I'll be there to let him out and comfort him if he's freaked out.
