You can easily convert an estimate into an invoice knowing that all the amounts and line items will be included.
Navigate to Estimates in the side panel, select your accepted estimate, navigate to the Actions button, select Create Invoice from the drop-down menu. Via this method, it will capture estimate line items and create your invoice for review, edits, preview and send to you client.
If you need to invoice a single line item, a part, or percentage of an invoice, refer to this Knowledge Base article Invoice a part, or percentage of an accepted estimate.