You can get this achievement on any Zone 1 or Zone 2 level in the game. The easiest way I've discovered to get this achievement is to find a past sign on a level, and then to find a vertical yellow or red bumper. Enter the spin dash attack mode by holding +. When you spin dash, you automatically enter the time travel mode. You will know this is happening because Sonic will be surrounded by a shimmering force field. Spin dash onto one of the vertical bumpers and just bounce up and down until you travel through time.