Welcome to the Community, @LL-TopDog. I can provide clarification on migrating to QuickBooks Online (QBO).
You may wish to consider waiting until your accounting firm sends the file in order to ensure that the changes made will reflect in your QBO company. Additionally, when importing data from QuickBooks Desktop into Online, all the data that's in QBO will be overwritten. While you are able to complete some of the setup, you may want to wait until the import is completed. I'm including an article which contains further insight into this process and contains a step by step guide for importing: Convert QuickBooks Desktop File to QuickBooks Online.
In the meantime, you may want to try the QuickBooks Online Sample Company, which is designed for a user to test out features and become better acquainted with the software. None of the information entered will be saved and can be a useful tool for learning. You can find additional information on this at the following link: How to Test Drive QuickBooks Online.
I want to ensure that you get the most out of QuickBooks Online for your business, so I'm including a link to tutorials: QuickBooks Tutorials.
Should you have additional questions about migrating or anything else QuickBooks related, please let me know. Have a good day.
