Check out this web page for details on how to first select a standard date format, save it as a Preset then edit that preset to do what you want.
I myself like to place images in dated folders with this format MMDD with no spaces, which would look like 0319, under the a Year folder that I have created at the beginning of every year. LR doesn't offer that option. So I picked one of the offered formats, saved it as a Preset, then modified it to do what I want.
I just imported several images that were all taken in 2016 but spanning several dates (hadn't used that camera in a few weeks). Once I click on my saved and modified preset they got put in dated subfolders under the Pictures 2016 year folder on my E drive.
It's pretty easy to do.