Purchase orders -vs inventory -vs- invoices

I understand the importance of tracking inventory accurately, MrsH2. I'm here to provide answers to your inquiries. 

In QuickBooks Desktop Pro Plus 2022, the inventory is typically added to the actual on-hand count at the time of receiving. Once a PO  is converted to a bill, then, this will automatically increase your quantity on hand.

For your construction business, the option to hold stocks once an invoice is created is unavailable. As a workaround, you can create a sales order instead of an invoice to record a sale that you plan to fulfill in the future. 

Here's how to create a sales order:

1. Go to the Customer menu, then select Create Sales Order.
2. Select the name of the customer.
3. Enter the necessary information.
4. Once done, click Save and Close. 

Regarding your preference for inventory to be tracked by piece rather than by square foot, you can choose Multiple U/M per item. You select this mode if you buy, stock, or sell any item in more than one unit of measure. For example, you should select Multiple U/M Per Item if you buy an inventory item by square feet and sell it by piece.

Here's how:

1. Go to Lists, then select Item List.
2. Click Item then New.
3. Select the type of item you want to create.
4. Click Enable under Unit of Measure
5. Choose Multiple U/M Per Item and click Next. 
6. Set the name of UM and its abbreviation.
7. Select the Default Units of Measure on the purchase form and sales form.

In case you need it, I'll add these articles that tackle managing PO and adjusting the quantity or total value of your products in QBDT for more information:

• Create purchase orders in QuickBooks Desktop.
• Adjust your inventory quantity or value in QuickBooks Desktop.

Please post again or leave a comment in this thread if you have follow-up questions about this or anything else QuickBooks. I'm more than willing to help. Take care always.