The tax forms that you see, and can download, when you log into your brokerage account are not what TurboTax imports. The brokerage or financial institution has to create a special data file specifically for importing by TurboTax. I guess it takes them a little longer to create that file, after they have created the forms that you see in your account.
The tax forms that you see online are designed to be read by humans. They are images, usually PDFs, of the IRS forms. It's very hard, if not impossible, for computers to read those and extract the data. The special file for importing is in a digital format that's designed to be read by a computer.
