Do I need to keep my uninvested cash in my account for a certain length of time in order to earn interest?

Margin interest at Interactive Brokers (IBKR) is calculated and charged as follows:

Calculation Method…

Interest is calculated by IBKR daily on a per currency basis, and is reflected on client statements in an accrued state. It is important to note that interest is calculated on settled funds, therefore, if you close a negative cash balance through a trade on Monday, interest will continue to accrue on the negative balance until the trade settles…

Lending income received through the Stock Yield Enhancement Program are calculated and accrued daily similar to interest on credit cash balances.  Interest will post to your cash balance on the third business day of the month for the previous month. …

If IBIE is required to apply WHT to your interest payments, we will do so at the same time any credit interest is paid to your account.

IBIE pays interest due on the uninvested cash balance in your account on the third business day of the month following the month in which the interest accrued. For example, interest accrued in January will be paid on the third business day in February.  …