A unique website dedicated to fishing information from Florida's Northern Big Bend. This includes the area from the Econfina River west to the Apalachicola River
When to raise it? Once you get on plane and when you slow down and want to idle into a place.
When to lower it? Getting on plane
How to use it to get up in shallow water? You can gun it with it up and lower it as you get on plane....Each boat is different, I can't do that unless I let the motor over half way down, any higher and it will blow out and over rev the engine (not good)....You can spin the wheel and gun it and ride the wake and get up...You should know the limitations of your vessel, if I do either on of these in less than two foot, it will cause damage to the fragile eco system on the bottom.
I would practice by trimming the motor down all the way and start at the lowest setting on the plate and work your way up till you find out the blow out height of the boat. As professor Chalk says every boat is diferent but this is how my boat works. I trim all the way down, use full bow down tabs, jp on 4 1/2" and nail the gas. as it takes off start letting up on the plate and trim to make up for the bow lift.