So from this I can reach 252 Activity If i post 14 posts in 14 days? Am i right?
Activity is calculated by the following formula.
The activity number is determined in this way:
time = number of two-week periods in which you've posted since your registration
activity = min(time * 14, posts)
If I count it correctly, you have posted in 20 different periods (you only didn't post in the period starting on Oct 14, 2014), and thus your current activity is capped by your post count but not the "time" value.
So to reach 252 activity, you just need to make 86 posts more (you have 166 as this moment) at any time you prefer.