My experience has been to start from the middle and work your way out. This was you it is easier to accommodate for the floor not being plumb. You can always call up or go be Lowe's or Home Depot location or online site for professional advice at no cost. Good luck with your project!
NEVER start from the sides. The walls are almost never perfectly aligned so if you start from the sides, all the tiles will be askew. What I do is stand by the door and place a tile about arms lenght into the room. I step back. If the tile looks alinged, then I can continue.