The Mk 4 Seat in the JP 3 and 4 had a 0.6 second delay from handle pull to primary cartridge firing to allow for canopy jettison after that the sequence was listed in the aircrew manual as follows:
As the seat ascends its guide rails, a static rod trips the drogue gun time delay mechanism. After a 1/2 second delay the drogue gun fires and extracts the controller drogue: this in turn develops the main drogue, thus checking forward speed and stabilising the seat in a horizontal attitude.
Also as the seat ascends, a second static rod frees the barostat time release mechanism. When free descent reaches 10,000feet, or at once if ejection has taken place below that height - and providing the g stop is not in operation - the barostat removes an obstruction to the gear train of the time release mechanism allowing it to operate. After 1 1/4 seconds the drogues and combined harness are released from the seat, the parachute withdrawal line pulls free of the guillotine gate and parachute deployment and seat separation follow automatically. At high airspeeds below 10,000 feet the g stop similarly impedes the gear train until the speed has dropped to a value safe for parachute deployment.