I'm here to guide you in entering your transaction, @wayne72.

You can create an item receipt for the first set of units you received from your vendor. Let me who you how.

1. Open the purchase order in question.
2. Go to the Create Item Receipts button.
3. On the Open POs Exist window, select Yes.
4. Choose the same purchase order.
5. Select OK.
6. Below the QTY column, enter 350.
7. Click Save & New.

Once you're ready to receive the remaining set of units, follow the same steps above making sure to enter the exact remaining quantity.

Here's an article you can read to learn more about item receipts: How to Receive Inventory With or Without a Bill in QuickBooks Desktop?

I'm adding these articles with the topics you can use while recording the common vendor transactions: The Vendor Transaction Workflows in QuickBooks Desktop.

It'll always be my pleasure to help if you've got additional questions about purchase orders. Use the Reply option below and surely I'll be here ready to assist you. Take care and stay safe!