If you are planning to solder your WS2812's on your own (4 wires and one .1uF must be solderen onto each diode), you should mind that this is quite tricky. You will definately need some extra diodes since you will most likely "burn" some of them. For each diode you solder, you should check if it works before attaching them together.
If it is possible for your project, I would recommend you to buy a 1m LED strip with 60 diodes (WS2812B or better SK6812 and best APA102). You can cut each diode out of the strip with a capacitor and some nice solder-pads already on it. This is MUCH easier to handle 