Inciting Competition Won't Work Here
Make Second Ave Q service your first choice for the Upper East Side. But Why?
I get it: you're trying to promote the relatively new Q train. But setting it up to compete against the 4/5/6 trains makes no sense. I'm not going to take the Q out of loyalty. It's just not gonna happen. The decision will be made (with the aid of Google Maps) purely based on logistics. I will simply select the most direct route.
Maybe it would be more effective to remind people how long it took to add this section of the train: that this will be the biggest extension to the Subway system in 50 years. That the subway began operating underground back in 1904, with railroad operations beginning as far back as 1863. That it currently has a daily ridership of around 5.5 million people! And that despite the age, scale and complexity of the network, and the planning required to tunnel under New York City:
"We're not done growing"
My 2.75$ on the matter