We have announced public preview of start VM on connect last week! Early adopters could use PowerShell or RestAPI to configure this feature for personal host pools. This setting lets you turn on your VMs whenever you need them. If you want to save costs, you'll need to deallocate your VMs by configuring your Azure Compute settings.
We are happy to announce that you can use the Azure Portal too! Navigate to the host pool settings of your personal host pools and watch out for the setting below.