What Time Is It Now?

Time dilation creates a different local frame of reference than what's on earth. Travelling so close to the speed of light, it could be some completely other day back on earth. You would need to observe local time in your space born inertial frame of reference. If you then magically stop, you're is to where you're not moving that fast any more. But if you're traveling and your internal chronometer says that it's sunday, than it's sundday for you. As long as you're even if, even, if a, your single sunday stretches years from an earth perspective, so you couldn't celebrate mass quickly enough on the spaceship to match an earth day