start with 2 fingers

If you want to move on to 3 later go ahead (thinking John Myung), if you see the need to that is.
If you need a simple analogy of learning bass it's like a MMORPG. As you level up you realise you only have enough skill points (in reality time and practise) to pump one skill. So there's no right or wrong to learning your lightning zap or fire storm, it's really personal preference, no matter what others say. You may start as a warrior or a mage - a finger plucker or a picker - but where you go after that is really your decision.
There'll be pure mages and pure warriors, but also fusion characters that can do both. Of course once awhile it's good to read a strategy guide, and in this case most of the guides say - start with the fingers