In short selling transactions, the borrowed stocks need to be returned within a certain period of time. The timing for returning short positions:

Return at any time: Generally speaking, you can choose to return the borrowed stocks at any time after short selling. There is not necessarily a fixed time limit for the return operation, as long as it is done within the contract or specified period.

Forced liquidation: If there is significant stock price fluctuation, or if the margin in your account is insufficient, the broker may trigger forced liquidation measures, requiring you to return the stocks or add margin within a short period. The specific trigger conditions are set by the broker and are usually monitored through margin ratios.