I used my right hand for the entire shave for about the first three months, before starting gradually with the left hand, just doing the easy bits left-handed. My left hand is nowhere near as precise as my right, and at first I thought I'd never shave that way. In the end I tried it because I couldn't get such a smooth result on one side.

I think that this had the advantage that I got the very basics of angle, lathering, and the feel when the razor is properly used without having to worry about using my non-dominant hand as well. I wouldn't force yourself to use the left hand right from the start, but I know others have different advice.