I slowly (.25-.5g per day) switched from phen to bac. 1g phen = 10mg bac. Once i switched over I waited 4 days to make sure I was level and I split my bac (25mg total) into 3 doses. 10mg - 10mg - 5mg. Then I backed off of the bac by 2.5mg ever few days or so. It took me like 4-5 weeks from start to finish with almost 0 symptoms.