Tile last, just make sure you have the room from tile to base cabinet counter top to fit your dishwasher in. I can't tell you how many times the tile guys tile into the dishwasher opening and guess what dishwasher would not fit. If questionable have them leave the front tiles out or you will never get it in. If you install the dishwasher before tiling, if it ever goes bad you may have to remove the front tiles to get it out.
Rich