Hi, and welcome to the Splatoon club~ ^.^
@Misti: It doesn't seem to take an overly-long time if you play really consistently (though every level does take more points to gain than the last). :3 I think I'm currently at level 16, myself, though I have missed the occasional day of playing since we got the game earlier this month (on the 4th). Also, I ended up focusing on clearing Octo Valley for a while. And then there are also the amiibo challenges, which I have been slightly distracted with... xD