Story point and capacity planning
I am very confused regarding the following situation:
In the backlog grooming session the team gives story point to the user stories within the backlog.
So when it comes to sprint planning, Scrum Master has a excel sheet which has the available time (capacity) for each person in development team (in hours).
My question is when do we assign hours to the task under the story points? do the tasks have to have hours before the sprint planning? (I am confused as it is being said hours should not be used; is this referring to hours not being used for user stories?)
There is no need to assign hours to tasks in Scrum, it is completely optional. There isn't even a need to break down a Product Backlog item into tasks, again optional.
If the Developers decide there is value in breaking Product Backlog items into tasks and figuring out the hours (this is an older tactic that I don't see used much anymore, and many consider wasteful), some of this will be done in Sprint Planning, and some of it will be done throughout the Sprint, as the Sprint Goal is inspected and the Sprint Backlog gets adapted resulting in updated tasks. Some teams will then use a burndown chart to track the remaining work (number of task hours remaining).
We now call it Backlog Refinement now, not grooming. Product Backlog items are the "what" and should be discussed there, not the "how". You shouldn't plan the "how", in other words, the tasks, until Sprint Planning and during the Sprint.
Scrum Master has a excel sheet which has the available time (capacity) for each person in development team (in hours).
It would be better if the Developers tracked their capacity, not a Scrum Master. A Scrum Master is not an admin for the team and shouldn't be tracking that stuff.
My question is when do we assign hours to the task under the story points?
When is the Sprint Backlog updated?
Is this required by management? If not, skip it. Focus on creating value for your product rather than obsessing over sizing and capacity.