Hello there, @tricoteuse. 

Recording an upfront deposit only applies if your customer pays you before performing any services. In your case, you can create an estimate for the $7,000 and invoiced the half amount. Here's how:

1. Click the + New button, then select Estimate.
2. Select the customer or project (job) from the Customer drop-down.
3. Fill out the necessary information.
4. Hit Save.
5. Beside the Amount section, click Create invoice.
6. Select the second option (50% of each line = $3,500).
7. Click Create invoice.
8. Once you created the invoice, you can record the payment when you received it.

I'm adding this article for more details: Set up and use estimates.

Just in case you'll start reconciling your accounts, feel free to check out this article for the detailed steps and information: Reconcile an account in QuickBooks Online.

Please touch base with me here for all of your QuickBooks needs, I'm always happy to help. Have a great day.