These units come in precharged (R410 in the condenser). The EPA rules are relaxed for R410 but that doesn't mean local rules do not apply. This is a one shot deal. If the homeowner gets the line set flare fittings installed properly Mr Cool says the residual trapped air isn't an issue and you can just let r rip. Most pros will still want to pull a vacuum and check for leaks before they open those valves because when the refrigerant is gone, it is gone.
