Running new light circuit with switch

OK so I ran 12/2 from the panel to a junction in the basement. Then ran 12/3 up to the switch. Came out of the switch with 12/2 to the junction box the ceiling fan is going to be mounted. I'm thinking I should have run the 12/3?
I'm getting rid of KNOB AND TUBE slowly and carefully.
I was anot electricians helper in the 80s before I decided to serve my country. I can't remember how to wire a switch. Instead of messing with the old wire in this 1920 house I tore the ceiling out and am running new from the basement up.This is the first of several light fixtures I will be changing out.
I'm going to attempt to load photos to help with diagnosis.
Thank you in advance.

Semper Fi

 

Welcome to the forums.

You don't necessarily have to use #12 wiring. For lighting circuits I usually use #14 to keep the clutter down in the switch boxes. You must use #12 if you are extending an existing circuit.

You need a three wire cable from the switch box to the fan if you plan to use two switches to control the fan. Even if you aren't using two switches now.... three wire is a better choice.

With the piece of installed three wire cable..... you will use the white and black. Cap off the red with a wire nut. Don't combine the red and black.

 

Thank You! How does the wiring go for a single switch? I'm lost hard core I have 2 posts on the switch. A black and a white coming off the fixture. We are going to use pull chains for the fan so I'm just tryingoing to get 110 up to it and break it with the switch. I don't know why I am having such a hard time seeing this.....think I've been looking at it too long.

 

At your switch box you will connect white to white. Connect one black wire to each side of the switch. Cap off the red wire.

At the fan it will be white to white, black to black(fan) and blue(light).

Since you are using metal boxes.... the ground needs to be attached to them also.

Be sure to use a fan rated ceiling box for the fan installation.

 

Thank you very much....................................

 

So the blue goes with the 2 blacks in the same wire nut?

 

If you're talking about the fan blue wire..... yes that and black get connected together.