Your first time with Dbol? If so, feel free to scale it back...No one said you need to run "4 weeks" of anything. Go by YOUR OWN BODY's feelings, not some "cycle".
The first time I ran Dbol I was planning 8 weeks. After about 4 weeks I developed horrible indigestion, insomnia, and lethargy...So I stopped taking it. I'm sure those symptoms were starting to lurk around week 2-3 but I wasn't in tune at that point, until I started burping up acid during training, and rolling over in bed until fucking 3am..
To this day whenever I run Dbol the same exact things start to happen, and I cut it off, my body is telling me I'm either toxic or something is just not right. I can usually make it 6 weeks now that I have a few runs under my belt..You will get used to it over time.