The earlier you get to your feet the better as far as steering is concerned. If you can get onto the unbroken wave, you have more options for steering. If you are still catching whitewater, then yes, you can steer but not very much.
Steering is actually not that difficult, it consists mostly of leaning the rail (edge) of the board into the water.
It helps to know a little about how surfboards work - I have posted this before, but it is useful to know so here it is again.
If you get a surfboard and run your hand down the rail from nose to tail you will notice that in the middle it is a nice rounded shape, as you get nearer the tail it gains more of a hard edge - on most boards the edge on the tail is actually almost sharp!
If you try to submerge a rounded object in water it will sink easier than a flat object. In the same way f you are going along a wave and you try to push the flat tail into the water it will slow you down because it doesn't go through the water as easily. If you press on a particular edge of the tail it will dig into the wave and turn in that direction (like if you dig a paddle in on one side of a canoe, it will turn that way).
So logically if you throw all your weight to the back and one side you will slow down and turn in this direction. The problem is you will probably slow down too much and the wave will overtake you.
The area under your front foot is designed to plane quickly through the water and putting your weight on the front will pull the tail out of the water more and speed you up.
So, the key to turning is to get the right balance between weight over the front and weight over the rear. Keep a low centre of gravity, ease some weight onto the back foot and lean in the direction you want to turn, if you want to turn quickly, put more weight over the back, if you are slowing down too much, put weight over the front again.
That probably doesn’t make a heap of sense, but look/ feel a board, and try it in the water, it will fall into place.
Here’s another tip I picked up, when you want to turn, get low, then turn your shoulders to point in the direction you want to go – this should apply the weight where it is needed, as you start to turn lean into it!
Hope this long winded waffle helps
Stick at it!