I think any of the times you mentioned would be appropriate. Anytime you can't handle how you are feeling is a good time to call. Even if they can't help, they can hopefully give you other suggestions or other resources to try. They are not wasting their time or resources talking to you. Talking to you is the purpose of that crisis line. You are just as important as anyone else that calls and your reason for calling is also just as important. They are there to help you anytime you need it.