firstly - this isn't a trigger movement as such - more giving the bowler the charge. As a theary it can work against medium dross bowlers as you have time to walk done the track at them, you make their good length balls into a half volley and that much easier to hit - not least because the bal will come on to the bat better.
But remember you are in the nets - usually a keeper should stand up to this kind of bowling - which means if you get it wrong you get stumped in a match.
This will be harder against quicker bowlers as you don't have time to walk down the track to them - plus their short ball wont be a long hop.
Without removing the charge from your armoury (it is a favourite of mine) you should get used to waiting longer for the ball to get to you - which is harder for a lower order batsman who has been itching for a bat all afternoon.
The important thing if you are going on the charge is to keep your head still and watch the ball really closely - and not find yourself looking at different Nimbus or Cumulonimbus