You'll almost certainly have to hire a certified test house, or more than one, to perform all the mandated tests and write the report(s) (e.g. 130 page report for a small box, plenty of screen captures of 'evidence').
An example (just an example) is MET Laboratories, Inc. - was used by one of our vendors once or twice. Obviously you'd probably choose one close to you.
Costs might be on the order of mid 5-figure$, up to the low end of 6-figure$. YMM certainly V.
You should probably approach them as soon as you have a preliminary design, and start to get quotes and select them.
With luck, you might even be able to tap into their expertise to review your design. But some may have policies against that (keep an arm's length etc.).