Based on FINRA guidance, "as promptly as possible" with respect to an Intraday Margin Deficit (IMD) is defined as meeting the IMD call within three business days of when the IMD call was originally issued.
On the fourth instance of not satisfying an IMD within three business days over a 12-month rolling period, IBKR will consider the client to be making a practice of failing to satisfy an IMD "as promptly as possible."