Some prefer to take it all aprox 45 mins before workout. People report awesome workouts, pumps and gains.
Others prefer to spread the dose throughout the day, in order to keep stable levels most of the time. I prefer the second option. If you're using 30mg I would split it in 3 doses of 10 each, split 6 hours apart. For example first dose at 9am, second at 2pm, third at 7pm. That would keep you with the dbol in your system most of the day, including the workout and the post workout nutrition.