Second, I would recommend keeping her in your room at bedtime. Brand new puppies are like infants, and when they go to a new home they are scared, in a new place, being taken from mama and siblings, in a place that smells different, sounds different, and has different people.
Lots of new puppies are comforted just be the simple fact of being in the same room with their people. They can see you, smell you and hear you breath, and that can be a big deal for them. You can put a crate in your bedroom. It doesn't have to be forever, you can transition her out to the laundry room as she gets older.
On to getting her used to being alone...
- try building up time, like you say. For the first few days, try to put her in her "room" and leave for 1-2 minutes. Yes, seriously, that short of time. But, do 1-2 minutes a LOT. Like 20 times a day. So it becomes normal. Then, the next day, try 5 minutes. A LOT, as often as you can. You get the idea.
- even with the building up time, she's still probably gonna be upset, since a few days doesn't give her much time to get used to it.
- even when you are home, still put her in her room, so she doesn't just associate being in her room with you leaving. You can put her in her room when you shower, or when you eat, or just randomly.
- some pups don't mind. They sleep most of the time they're alone anyway.
- tire them out before you leave. Exercise her before you leave, really get her good and tired.
- you can leave a frozen, stuffed kong for her. We use peanut butter in ours and freeze them overnight. It keeps our dogs occupied.