Split second spell protection

[Schubydoo]

If you cast a spell and someone in response force of wills or tries to disrupt it, are you able to cast a split second spell in response to your first spell to prevent their counters from being able to go in the stack? And if this works do you have to do it before they cast their counters or can you wait to see if they will use a counter?

Ty!

[griffin131]

If you cast a spell and hold priority, then, say, {Krosan Grip} only triggered abilities can be put on the stack.
Once Grip resolves, however, they can counter your original spell just fine. Split Second doesn't "lock" the stack forever, just while the Split Second spell is resolving.

[Mattao19]

What he said.

Split Second "locks" the stack until say {Krosan Grip} or whatever Split Second spell resolves. As soon as it resolves the stack goes back to normal and your opponent can respond to your other spells.

Important to note: {Counterbalance} can counter Split Second because it's a triggered ability not activated so be careful with that

[Kaylesh]

If you cast a spell and someone in response force of wills or tries to disrupt it, are you able to cast a split second spell in response to your first spell to prevent their counters from being able to go in the stack? And if this works do you have to do it before they cast their counters or can you wait to see if they will use a counter?

Ty!

To add to the other responses:
You can't respond to an action, such as announcing a spell, before you get priority.
In the case of the casting of {counterspell}, you can respond only after the spell has hit the stack targeting your original spell.
If you cast {Krosan grip} after that, the counterspell will still be there and will stop the first spell after Grip resolves.