With mine, it took me 7 or 8 months to even begin to trust. I have a long history of trauma, for reference.

It was an interesting process- while I didn't trust him at the beginning, I had a feeling in the back of my mind that eventually, if we worked hard, I might be able to trust him. The difference between me and another therapy-goer might be that I've never trusted anyone, at all. So coming to trust this person was a big deal and involved a little bit of him earning my trust, and me learning that some people are worthy of being trusted.

I still have regressions where I or another part panics and then there's much reassuring to be done. I think for me learning that he could be trusted was a big part of our work together.

I think for a person with a trauma background, the timing of the trust process is very individual. The key for me was thinking I might possibly be able to trust them someday.

For the record, I have another T who is mostly a paid professional to me. We are not really bonded. But it's ok, just a different dynamic. For that T our work is more external and does not intrinsically involve our personal relationship with each other.