It's either an attorney/client relationship or it's not. An employee can be in that relationship without formally hiring or paying the person.
Regardless, it either is or isn't.
You're talking about two totally separate things. One you just brought up is whether they have a privileged relationship (doctor/patient, pastor/penitent, attorney/client) at all. If they didn't and do not they can talk about whatever they want at any time. But if they had such a relationship, they could not tell anything confidential at any time, UNLESS:
1. They had specific information about a crime, AND;
2. This information was about a crime that was going to be committed in the future, AND;
3. The crime would likely result in death or great bodily injury.
That is the only way they can break the privilege and reveal confidential information.
The other thing that you previously brought up is whether they would be breaking the law by failing to reveal information related to a crime they now realize has occurred, but at the time they heard it, it was only speculation. The answer is no. In fact, they would be breaking their ethical duties to the client as could get in trouble with the state bar, for revealing such information.
Just knowing about a crime and keeping silent is never criminal unless it's abuse and you're a mandatory reporter, or you assist the perp in getting rid of evidence, or creating an alibi, that kind of thing.