I don't know the answer to your question and I think it might be somewhat different for each person. But on the steroid.com Dianabol profile, the author recommends 10mg of dbol per day as an option for bridging. Below, I cut and pasted the link and the selected info from that page.
http://www.steroid.com/Dianabol.php
"In order to successfully bridge between cycles (and this means using a low dose of AAS, in this case dbol), you need to recover your natural hormonal levels to pre-cycle levels or to within acceptable parameters, and then you start your next cycle. The idea here is that you wont lose any gains, but rather a low dose of an AAS will help you maintain them. Typically, you'd use around 10mgs/day of dbol and combine it with an aggressive Post-Cycle Therapy (PCT) course of Nolvadex (and/or Clomid) and HCG. This would give you full androgen replacement from the Dbol and a shot at recovering your natural hormonal levels via the other stuff you are taking. Remember, the 100mg/day dose of dbol in the study we looked at earlier did not suppress Test, LH, or FSH to a degree that would make recovery impossible and certainly not with 1/10th that dose in conjunction with an aggressive PCT."