You can set your backup to Automatic, Schedule the Backup and set it to be Saved in your Google Drive with the following instructions:
1. Go to the Contacts tab and tap on the Backup icon.
2. The screen below will appear, tap on Auto Backup.
3. After you've tapped on Auto Backup you will get the following options:
Auto-Backup: Automatically backups your address book.
Save in Google Drive: Saves all your backups in your Google Drive and avoids you from losing data.
(PLEASE NOTE-You must be connected to your Google Drive to set your backup to be saved there).
Backup Schedule: Set the frequency of how often to backup your contacts.