Hey @CGarman,
Welcome to QuickBooks. It really depends on how you received payments and when. If you expect to be paid in the future, send an invoice, if you get paid at the time of sale, record the transaction as a sales receipt.
An easy way to keep track of this is to contextualize the process. Think about how you'd receive documentation of a sale when you go to the store to buy milk - do you get invoiced, or a sales receipt for the milk? And what determined that?
I'd recommend checking out The Fundamentals of QuickBooks Online. This covers very basic money-in and money-out workflows.
You could accept their advanced payment and record it as a sales receipt to finish the transaction and record it in QuickBooks. However, if you're receiving advanced payments that are refundable (and more like a deposit), there's a separate workflow. Here's how you'd set up a deposit - this method is the best way to stay compliant. Holding money requires a very particular process.
@CGarman has provided some great insight, but I would avoid doing any Journal Entries, it's a bit too powerful for what it sounds like you're trying to accomplish at scale.
What do you think?