1 Round Casting Times and Aiming

[Please Don't Kill Me]

Okay I have a quick question, do I have to aim a spell with a 1 round cast time (like sleep) when I start to cast or when the spell goes off?

[spalding]

When the spell goes off.

[Please Don't Kill Me]

Just out of curiosity do you have a reference for that in case my GM asks?

[Gauss]

CRB p213 second line wrote:

You do not have to select your target until you finish casting the spell.

- Gauss

[Bregen]

Thanks.