The initial snapshot will start with only a few MB in size (depends on whether the VM is powered on or off as well as the data change rate in the guest OS). However, it can grow up to the provisioned size of the virtual disk.
When creating snapshots in another location, keep in mind that virtual disks with snapshots are used as a chain, where the latest chain link is used for R/W and the others are used for Read-Only. Placing a snapshot on a slower tier will impact the VM's performance.
André