Early initiation of transmission of data in a network interface that includes a dedicated transmit buffer is provided in a system which includes logic for transferring frames of data composed by the host computer into the transmit buffer. The amount of data of a frame which is downloaded by the host to the transmit buffer is monitored to make a threshold determination of an amount of data of the frame resident in the transmit data buffer. The network interface controller includes logic for initiating transmission of the frame when the threshold determination indicates that a sufficient portion of the frame is resident in the transmit buffer, and prior to transfer of all of the data of the frame into the transmit buffer. The monitoring logic includes a threshold store, which is programmable by the host computer for storing a threshold value. Thus, the threshold value may be set by the host system to optimize performance in a given setting.