The opening time of a margin position is handy to know since any open margin position is subject to the margin financing term limits. For US-based clients, any open margin position will be auto-liquidated after 28 days and for clients based outside of the US they will be auto-liquidated after 365 days.
To check the opening time of a margin position:
1. Navigate to the Positions-tab under the Trade-tab on your account
2. For the position, click on the order ID to open the details of the position
3. On the open positions details page, click on the order ID on the right-hand column to open the details of the parent order
4. On the details page of the parent order, look for the closed time of the order. The closed time of the parent order of the position is when the position was created