Post Ejection Para Descent Drills

[lesterpk]

G'day all, due to a change in lifepreserver in use a question has arisen at work to do with post ejection para descent drills. There is a disconnect between what our team of life support experts think and what the aircraft flight manual says to do.
We are using the Survitec Flight Jacket https://survitecgroup.com/survitecprodu ... epreserver and the main question is, do you recommend/teach in your drills, to inflate the jacket (one or both chambers?) while under parachute canopy, or enter the water un-inflated and let the automatic inflation unit take care of it?
Our previous teaching is to not inflate before water entry, however the flight manual says to do so.
Happy to have some input here based on your own experience or teachings.