this is how SD works for me:
Mass gains begin day 1, for the first week i gained about a pound a day, and then it slowed down gradually until it pretty much flatlined after week 3 (ran for 3.5 weeks).
Strength gains started immediately but were more consistent, i gained about the same amount of strength every week including week 4, and gained strength for about another 5 days post cycle.
Now, because of the rapid weight gain people like to think they should run SD for 2 weeks as mentioned above... What I would like to point out is that initial weight gain is more glycogen and waterweight than anything else. If you gain 10 pounds on the first week and quit then, you're not up 10 pounds... you're bloated 10 pounds and you haven't gained anything worth keeping.
Also, easy come, easy go. The weight that gets slapped on real fast initially is the same weight that disappears during PCT. And as far as actual LBM gains go, you will retain more if you spend slightly more time on cycle, because the longer you spend at the increased weight, the more the gains will solidify and your body will get used to being that big.
WHICH is why I don't like short cycles... I think SD should be run for 4 weeks, 10/20/20/20 or so. Stop early if sides get to you, but IMO superdrol sides are stupidly exaggerated.
my 2 cents.
[i ran 10mg days 1-5, 20mg days 6-18, 30mg days 19-25, only side i experienced were very mild back pumps, which i did not try to mitigate because they were so negligible. Also I ran this after bridging from 4 weeks of Epi]