Hello there, @IngeBerge.

I’m here to share some information importing bank transactions in QuickBooks Self-Employed.

When connecting for the first time, we pull as much of your transactions as possible. The amount of data we can bring in depends entirely on your bank. 

Since you only need to import transactions from 01/01/19 going forward, you’ll have to export from the bank and upload them to QuickBooks. 

Here’s how to export data:
1.    Go to your bank’s website and sign in.
2.    Select the account with the data you want to export.
3.    Look for a button, link, or other info that describes downloading or exporting data.
4.    Set the date range you want and be sure to specify CSV as the file type.
5.    Follow any remaining instructions to finish exporting your data.

After which, you may start importing transactions to QBSE. To do that, follow the steps below:
1.    Go to the Gear icon and select Imports in the drop-down menu.
2.    Select the account you want to import to. Make sure it’s the same account you downloaded data from.
3.    Follow the instructions to finish importing data.

Please check out this article for more details: Import transactions from earlier date ranges.

Before performing the steps I’ve given above, you will have to get rid of the past downloaded transactions first. Here’s how:
1.    Go to Transactions from the left pane.
2.    Click the drop-down on the box next to the Search transactions field and select  Custom date.
3.    Then, enter a Start date and End date.  Doing so will allow QuickBooks to only show transactions within those dates.
4.    Hit Apply.
5.    Place a check mark on the box next to DATE to select all the transactions you want to remove. 
6.    Choose Exclude from the options given above.

For more information, take a look at this article: Exclude or delete transactions.

That should get you pointed in the right direction. Let me know if there’s anything else I can do to help, I want to ensure your success. Wishing you the best!