I hope April 5th is the day Klingon's stole warp drive from a Freighter.
That would be the Pakled.
Seems the Klingons already had interstellar travel before the Hur'q came.
According to the "Star Charts" that were used for this game, they did so during Kahless' own lifetime.
First Contact Day would be a different day for each species of the federation. Would it not be better to celebrate FEDERATION DAY.
Star Trek universe is based on Human, and some aliens we don't really care they met on the way to success It's about the same than the Terran Empire, except Starfleet assimilated others peacefully.
First Contact day is the Human one.