Should I scan receipts into Quickbooks that I accumulated prior to purchasing the Quickbooks software?

Let me give you a warm welcome to the QuickBooks Community, @Archerconsults.

Yes, I agree with scanning receipts into QuickBooks Online (QBO) if there are financial records that still need to be settled. This is because you may need to upload receipts to address missing transactions or match them to previously entered transactions to ensure they are in the correct account. To check if everything is accurate, I suggest running reports in QBO. 

Additionally, you might also want to consider adding receipt attachments to transactions using the paperclip feature at the bottom of the screen of an individual transaction. This allows for better recordkeeping and easier bookkeeping for your accountant.

 
Feel free to check out this website to have resources at your disposal in navigating QBO: Self-help articles.

You're always welcome in the QuickBooks Community should you have further questions about uploading receipts to QBO. Take care.