GNU date in MacOS

The GNU date utility is provided in the HomeBrew package coreutils as gdate.  Install with HomeBrew.

[~]
scott@bargamac$ HOMEBREW_NO_AUTO_UPDATE=1 brew install coreutils
==> Downloading https://homebrew.bintray.com/bottles/coreutils-8.32.mojave.bottle.tar.gz
==> Downloading from https://akamai.bintray.com/5d/5da6cb9dbc0a8144480dde2fb78eb0a5a1710490afc3697174f7e261ec69763f?__gda__=exp=1587689482~hmac=42c0483b851c
######################################################################## 100.0%
==> Pouring coreutils-8.32.mojave.bottle.tar.gz
==> Caveats
Commands also provided by macOS have been installed with the prefix "g".
If you need to use these commands with their normal names, you
can add a "gnubin" directory to your PATH from your bashrc like:
  PATH="/usr/local/opt/coreutils/libexec/gnubin:$PATH"
==> Summary
🍺  /usr/local/Cellar/coreutils/8.32: 476 files, 8.8MB

Note the path to all the coreutils which can be added to your system $PATH