How can I create a GTD (Good-Til-Date/Time) order?

You can see how many days are left until the last trading day for an option by adding the "Days to Last Trading Day" column to your TWS or Mosaic page. To add a column to your TWS page, right click on the tab/page header and select Layout. Click the Market Data Columns tab and expand the Contract Description section on the right side. Select "Days to Last Trading Day", click the Add button in the middle, and you should now see those columns on the left side under Shown Columns. Once finished, click the Apply and OK buttons at the bottom of the window…

You can create a bracket order (OCA) for an existing position by adding the OCA Group column to your TWS. Right click on the tab header and select Layout. Make sure you are on the Order Columns tab and find the Order Attributes section on the right under Available Columns. Click the green plus sign (+) to expand the section. Click OCA Group and click the Add button in the middle. You should now see the OCA group column on the left side under Shown Columns. Once finished, click the Apply and OK buttons at the bottom of the window…

An order that uses the good after time/date field is held in the IBKR system and submitted to the market on the date and time you specify.

Classic TWS…

You can find the Opening and Closing prices for your stocks by adding those columns to your Trader Workstation Watchlist or Portfolio pages. Right-click on the tab header and select Layout. Make sure you are on the Market Data Columns tab and find the Prices section on the right under Available Columns. Click the green plus sign (+) to expand the section. Click each price column you are looking to add, in this case, Close and Open, and click the Add button in the middle. You should now see those columns on the left side under Shown Columns. Once finished, click the Apply and OK buttons at the bottom of the window…