Yes, definitely!

1. From the dahsboard head to Auctions and click Manage on your campaign.

2. Click Items in the left sidebar, then click on the item you would like to edit.

3. Click on Advanced along the top bar. Scroll down to the "Start and end dates" section and input your dates. Remember to click Save.

Please Note: The actual payment processing and fulfillment of the item will still happen along with the rest of the Auction (at the end, when you click "Close Auction", and "Charge Cards"). Having an item end early really just means that only the bidding stops at the time you set.