Nice to have you in the Community. I'd be glad to help you with reconciling.
Even if you have never reconciled before, this process can be initiated at any time. This is also a great way of helping to ensure that your books correlate with what's in your bank account.
The following link is a resource hub of articles to help a user with reconciling in QuickBooks Online: Reconcile Hub. From here, you can access resources to help you with every step of the reconcile process.
I'm confident that this will help you on your journey.
Please know that the Community has your back, so don't hesitate to let me know if you need anything. Cheering you a wonderful 2019.