retry with initial delay

[ASaiAnudeep]

Is your feature request related to a problem? Please describe.
In some use cases, we might want to have a initial delay longer than the normal delays between each retry.

Describe the solution you'd like

spec.retry({ count: 3, delay: 1000, initDelay: 30000 });
// or
spec.retry(3, 1000, 30000);

Describe alternatives you've considered
NA

Additional context
NA