There is no place where you can find an overview from all Hyper-v snapshots in the VMM Gui.
In this situation PowerShell is your friend. With a few lines of PowerShell code is this overview simple to make.
Run this commands in an elevated PowerShell prompt where you installed the VMM Console:
#Connect to SCVMM Server #Checkpoints
$vmmserver = "VMMSERVER001"
Get-VMMServer $vmmserver | Get-VMCheckpoint | Ft Name, VM, Description, AddedTime, ModifiedTime -auto