When printing pages (5x7 folio) that are smaller than letter-size paper, Dorico automatically justifies the page in the center of the paper. I would like to have the page located in the upper left-hand corner. How do I accomplish this?
David, I think your best choice would be to create a sample project in Letter format and then in Layout Options->Page Layout adjust the margins in a way that you will have a Folio Format left in which your music will be placed. Basically you would have to increase the Right Margin and the Bottom Margin.
Then use this project as a starting point, when you come across the situation again.
 It would be interesting to know, what happens, if you do your printing not from within Dorico but with .pdf versions of those files. So print the folio document to a letter paper.
In my experience, only pro-DTP apps like Photoshop, InDesign and Illustrator have options for where to place a page on a sheet.
Generally, the OS’s printing system is configured to print the page to the center of the sheet.
Are you just trying to make trimming easier, or something else?
Yes, exactly! I’m trying to reduce the amount the trimming required.
If this is something you’re printing yourself, as opposed to a comercial printer, you could export a pdf out of Dorico into Affinity Designer and move the page where you like.
Not sure if this is worth the extra steps and expense to avoid some trimming. Depends on how much you need to do.
If going to a commercial printer, my experience is they don’t care to much about ease of trimming. They are usually set up to easily accommodate multiple sizes and prefer it centered in the page. At least we did in the print shop I worked in.