Hello, rachelhale.
For me, it will save more time if you start new with QuickBooks Online. Just make sure to get the correct balances from your books so you can just create a trial balance through Journal Entry.
Moreover, you can import your chart of accounts, customers, suppliers and Products/services list from QuickBooks Desktop into QuickBooks Online. For more information about this process, please check this article: https://quickbooks.intuit.com/community/Reports-and-accounting/Export-then-import-list-data-into-Qui...
If there's anything else we can do for you, please don't hesitate to reach out. We'll be here to help you.