You'll miss out on four moves: thunderbolt, lvl 26, agility, lvl 30 thunder lvl 41, and light screen lvl 50. I suggest you wait until you get your pika to lvl 50 before you evolve. Light screen is pretty handy.
Also, next time please use the pokedex. It saves you and me a lot of time

Oh, and welcome to the forum!
~Dark_Force ;246;~