When Java was under 1 year old we only left her alone for 4-5 hours max. We kept up the same pace until we started noticing how little she really did go out when we were home. She'll go out at 8pm the night before, then sleep in, lounge around and most often doesn't even ask to go out until noon! She can really hold it - there are no accidents in the house.
Now, we often leave her in the house running free while we are at work. It depends on whether or not she's "fully loaded" or not when we leave in the morning! If she doesn't do it all before we leave, we put her in the laundry room with the gate.
I guess the answer is to watch your puggy when you are at home and see how long (more/less) they can hold it. Leaving is never easy though...can't help you with the emotional part since I can't deal with that myself!
Jeannette and Ruby
My beloved Java, at the rainbow bridge and sadly missed
My sweet old man Curly, at the rainbow bridge. We miss that boy!