Just a heads up, learn Nachi’s material inside and out, then gain experience, and ask questions. There also some great books out there on PCAs, and lots of videos on Youtube. But with that said, there is no requirement out there on the client’s side - anywhere - to have the assessor be ‘certified’ to a PCA standard. The big clients look at the actual standard you follow more than anything else. Which, if you look at standards like E2018, emphasize qualifications over certifications (E2018 mentions certifications, but only in the context of a training topic certificate or CEU certificate). The body of experience, the body of education, and the body of training matter more. This is all then summarized in the Statement of Qualifications that accompanies every report.
As an example, I actually had a client ask me if we were ASHI certified to do commercial work. It took every ounce of strength in me to not laugh out loud. I patiently explained to him what he was suggesting, and then we had a nice chuckle about it.
Also for the record, we train our people for a full month before they go in the field. 8 hours a day, five days a week, for 4 weeks. And once they clear that, they shadow the senior folks for 4 or 5 projects, and get assigned a mentor for their first year.