About a year and a half.
To be honest it's not "easy" to use. The guiding principle behind mainline packages is that everything has to be built from source, so most somewhat unpopular things are missing from the mainline channels.
To use it like any other distro you're going to need to learn how to write packages fairly quickly. Luckily the main draw of guix is the entire OS being based on guile so once you get a little under your belt you can just read the specs from other channels to see how a package is written.
Took me maybe a week to start writing guix packages.
There's also The toybox