It's not really possible to confirm off of f.S because it happens way too quickly for you to react. Instead, you'll need to buffer the next action based off of what you think will happen.
Here are the possible situations on block:
Blocked normally
IB'd
FD'd
High Blitz (we'll count that as a block)
Here are the possible situations on hit:
hit normally
CH
However, this can have many permuations: based off these variables:
distance
early or late into active frames
whether they were crouching or not
Here are the things you can do after hitting them with f.S in each situation:
It's not really possible to confirm off of f.S because it happens way too quickly for you to react. Instead, you'll need to buffer the next action based off of what you think will happen.
Here are the possible situations on block:
Here are the possible situations on hit:
Here are the things you can do after hitting them with f.S in each situation: