I don't understand your question really? Are you asking what the best time is to take a snapshot or take a backup after a snapshot or from a snapshot?
In technical terms, snapshots essentially give you the ability to take a snapshot at anytime. Performing a backup of the snapshot then essentially doesn't affect actual production data, etc. You can literally backup the data within the snapshot at anytime.
In most other scenarios, most would perform backups when the systems aren't getting used or lightly used, primarily at night. With eCommerce now a huge part of our computer world, most deal with systems always in use, all times of the day.
Technically as a Backup Administrator myself, you should never solely rely on snapshots. They're perfect for rolling back for a quick fix if some disaster happens, possibly only losing a day worth of data changes. But they're not efficient for long term retention policies and a backup solution along side snapshots should always be setup to secure your data.