my line for snapshots

btrfs subvolume snapshot /source/drive/folder/ /source/drive/folder/.snapshots/snapshot-`date +"%Y-%m-%d-at-%I-%M%P"`

this will create a snapshot with date and time attached to the snapshot name

you can more info here

https://btrfs.wiki.kernel.org/index.php/SysadminGuide#Managi...

make sure to remember to delete old snapshots, otherwise you'll run out of disk space and not know where it went