In my opinion, you should always add the calories slowely. If your body is used to you eating 3000 calories, and you are not putting on weight, then up it a few hundred, you should start gaining weight. When that weight gain slows down, that means that your body is beccoming accustome to the new calorie level, then you have to up it a few hundred more. I reccomend that you up the calories every week or two, by 100-500 calories. If you are adding accessive fat than either reduce slieghly or stay the same. Your body slowly getts accustome to whatever you eat, as it is always trying to maintain a balance.
Your gear was not fully active from the begining, although it was active. 4-5 weeks is when it is the most active in your body.
The best way to bulk is to find a calorie level that your body adds almost no bodyfat, but still adds a little all the time. anyting more than that, in my opinion will only help you get fatter.