@Kale, Vaibhav As per response from the backend team improvising VMSS start time is being worked upon and is in pipeline.
As mentioned in comment above we are doing work to increase the provisioning time for VMSS instances.
Some general tips on VMSS provisioning times:
•Store your custom image in a Shared Image Gallery, and create your VMSS using a Shared Image which will move it to a more modern stack
•Create your VMSS with singlePlacementGroup=false, FDCount=1. That will relax constraints on your VMSS and allow us to allocate and return them as quickly as possible.
Hope it helps!!!
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