I just now transferred from QB desktop to QB online and connected to my bank account. It asked for start date for collecting data and I put in the wrong date. Help?

Hello there, @dianejanes2-gmai.

I'm here to ensure you're able to keep your accounts updated in QuickBooks Online (QBO). This way, you can effectively manage your transactions and keep your books accurate.

When you connect your accounts to QBO, your transactions for the last 90 days will automatically be downloaded. Don't worry if you've inputted an incorrect start date (01/01/2020) because you can exclude the transactions prior to 01/01/2021 to avoid duplicates. I'm here to guide you how.

1. Go to the Banking menu.
2. Select the tile for the account you want to review.
3. Go to the For Review section.
4. Sort the list to only include the dates/transactions you need.
5. Click the box to select all transactions or manually choose the ones you need to exclude. 
6. Select the Exclude button.

I've attached a screenshot below for your reference.

After that, you'll have to review and/or match all your downloaded bank transactions to the existing entries in QBO. With this, you can keep your account updated. You can refer to this article for the detailed steps: Categorize online bank transactions in QuickBooks Online.

Once done, I'd recommend reconciling your accounts every month. This way, you can effectively monitor the growth of your business using QBO. For the step-by-step guide, you can refer to this article: Reconcile an account in QuickBooks Online.

Also, I'm adding this article to learn more on what to expect when you switch from QuickBooks Desktop to QBO: Migrate from QuickBooks Desktop to QuickBooks Online.

Please don't hesitate to comment below if you have other concerns about managing your transactions in QBO. I'm just around to help. Take care always.