Incorporation is the start line, not the finish. The weeks after your CR is issued carry their own set of obligations, miss them and you accumulate quiet liabilities.
The essentials
Activate ZATCA and assess your VAT position. Register employees with GOSI and configure WPS. Confirm your national address on Ejar. Open your corporate bank account. Establish bookkeeping from transaction one, retrofitting books is far more expensive than keeping them.