This is why I have suggested the use of an external Keyer such as the K16 EXT by K1EL which has Lead-In and Tail-Timing built into the Keyer functions, this enable the Transceiver PTT to be activated by the Lead-In Timer by (x ms) prior the the first CW element and a Tail-Timer to hold the PTT (y ms) after the last CW element. this every old technology from the Tube Transmitter and Receiver Days and still works to day, the old Mercury Vapour Tubes used as High Voltage Diodes has a tendency to create Chirp but if the transmitter was keyed on a few ms before the first CW element was sent the Chirp was much reduced.
Please Note: at 60 WPM the computer polling of the Keyer state and the transmitter PTT state is every 17 ms
VE6LX