You don't need to answer everything at a time; you can save the incomplete questionnaire and finish it later.
It will take approximately a few hours to a few days to complete the questionnaire and upload all required documents. This depends on your company size, cybersecurity maturity level, and whether you have all the requested information (including documents). Please note also that you can answer the questions in any order you want.
Please always remember to save the page you are working on before closing your questionnaire, using the commands at the bottom of each page.