I find that for me personally, I don't notice a difference taking dbol all at once or split through the day. For guys that tend to suffer from side effects such as gyno or high blood pressure, I would suggest splitting your daily dose up in 2 to 3 doses. The half life is short. Maybe 5-6 hours. If sidea aren't a problem, all at once is fine. I would take dbol every day. If you are taking your whole dose all at once on training days, I would take it on non training days at about the same time. Even with the short half life, it takes time, for me 7 to 10 days, to really feel dbol "kick in". The hormone has to build up. If you skip taking it on nontraining days, you are going to interfere with building your blood levels up. Even if some guys get an enhanced effect from taking some dbol preworkout, I don't think it is going to be as good as the effect you get from having consistently elevated blood levels. 

Be sure the check your blood pressure through the cycle. You can't always "feel" high BP, but it can be very dangerous