You learn to trust when you have true remorse and honesty, transparency.
You are very early on in this. Broken NC is a common thing, not that it makes it ok, but is does seem to take a few false starts for R to take.
If your gut is screaming at you that something is not right, then it is probably correct. Keep digging, keep looking, and call him out on anything that you deem unacceptable.
As far as having extra time, and MLC he needs to find a hobby other than having an A to fill his time, golf, fishing, hiking, cooking and cleaning whatever. He needs to get busy so his mind is wandering back to the A, and how good it made him feel.
To answer your questions
"How long does it take?" It takes as long as it takes WS to be honest, be committed and transparent, plus time. In my case it was a year. Someone else said this earlier this week, and I think it's an accurate description "Each time you snoop, or dig, and find nothing its like a $1.00 in the trust bank" It takes a lot of dollars to feel safe again.
"Can it ever be like it was before?" No - Your M will never be the same. I will have a scar forever. Does that mean it will be forever broken, NO it does not. Our M is better now post R than it was for several years pre A .
"What did I do to help in the trusting phase?"
I allowed H to feel safe when he was really out of the fog and NC was securely established for a while. I thanked him each time he told me OW was fishing and trying to talk w/ him.
That's it. The rest is on him.
The WS has to do the work, they have to realize what they have done, the damage they caused, and be remorseful for it, and be absolutely transparent in their actions.
((((andstrength))))