The article will show you how to import custom form styles for invoices or estimates. There isn't an estimated time-frame on when you can import Purchase orders and Sales Receipts. The good thing is that you can customize Purchase Orders and Sales Receipts right from your account. Check out the following article:
I recommend you to leave feedback to our engineers about importing Purchase Orders and Sales Receipts. You can do this by clicking the gear icon and looking for Feedback. New product ideas and improvements are largely based on the feedback we get from other users like you.