personally, and my knowledge is limited here, but i'd do 50mg from the start. promagnon is a very mild compound, so 2-3 pounds in a month is about what to expect. it also has a very long half-life, and taking a dose of anything before bed can give you sleep issues. most compounds are active for 3-4 hours. promagnon's half-life is around 6-6.5 hours - sometimes longer.
for those reasons, i'd dose one tab in the morning, the other around lunch time - provided you FINISH your work out by 6pm). if not, adjust the last dose accordingly.