CPF balances used for interest computation are affected by the transactions in your account.
Contributions, including cash top-ups, received this month will start earning interest next month.
As for CPF transfers, in general, the recipient will earn interest on such monies received in the month of transfer, and the giver will not since the monies had been deducted. If the giver had received contributions and transferred them, the recipient will then earn interest next month.