1st off, you are growing more than one plant...right?

2nd, never cut off healthy leaves. the plant needs them all especially in low light such as yours...which is probably the reason why it's not growing faster. or it could be a runt...it happens. which is why one should always cover the bases and plant twice as many as one needs.

3rd, do NOT go to 12/12 this early. as soon as they begin alternating branching pre-flowers will appear and that's usually around the 6th week from sprouting. so keep your 10x magnifying glass handy and start getting used to the parts you'll be keying in on when it's time (every serious grower has at least one 10x mag glass).

4th, patience...