CL65 FLT ATTENDANT WAS NOT IN HER SEAT FOR THE TKOF.

Narrative

AFTER CLOSING THE MAIN CABIN DOOR IN PREPARATION FOR DEP; I WENT TO FLT DECK TO INFORM THE CAPT THAT CABIN WAS READY FOR PUSHBACK. I THEN COMPLETED ALL DEP ANNOUNCEMENTS AND REQUIRED DUTIES; THEN BEGAN FINAL WALK DOWN. COMING BACK TOWARDS THE COCKPIT; THE FO GAVE THE PREPARATION FOR TKOF PA; PROCEDURALLY WE ALL SHOULD BE ALLOWED AT LEAST 1 MIN TO ACCOMPLISH ALL TASKS. I PROCEEDED FORWARD TO THE COCKPIT AS THEY BEGAN THEIR TKOF ROLL. I CONTINUED WALKING TO THE COCKPIT TO LET THE CAPT KNOW THAT THE 'CABIN WAS SECURE;' WHEN I NOTICED THAT THEY WERE IN THE EARLY PART OF THE TKOF ROLL. UPON PRESENTING MYSELF IN THE COCKPIT DOOR; THEY BOTH NOTICED THAT THE CABIN WAS NOT SECURE FOR TKOF. AT THIS TIME; THEY ELECTED TO CONTINUE THE TKOF. ONCE NOTICING THAT THEY WERE NOT GOING TO STOP FOR AN UNSECURED CABIN; I PROCEEDED TO CLOSE THE COCKPIT DOOR; UNLOCKED AND OPENED MY JUMPSEAT TO SIT AND RESTRAIN MYSELF AND WAS THROWN FORWARD AS THE PLANE LIFTED OFF THE GND. I MANAGED TO PULL MYSELF BACK INTO MY JUMP SEAT AND LOCK MY LAP BELT.