There is a very big difference between 3mg and 4mg. 3mg is my standard dose. It's fully strong, but you'll probably still be able to function pretty normally even during the peak. There will be pretty strong visuals most likely. I like to take this dose for camping or hiking, or pretty much any other activity. If you just sit around at home it can get a little intense with the energy I've found, and be uncomfortable for a while. 3mg is a strong dose. I also sometimes take 3.5 if I want it to stronger than that, but not as strong as the 4mg level.
4mg is a different ballgame... I've only taken it a couple of times (and I've used DOC many, many times over the years as it's pretty much my favorite all-around psychedelic). For me, it actually begins to incapacitate you here. The peak hours (which as you know are a good 6-8 hours) I spent sitting in a chair, lost in my head half the time. I was listening to music. I actually felt a little sedated during the peak, I don't think I'd want to take that dose and be out doing something. It gets much more psychedelic at this dose but I can find it to start out being rather confusing and cloudy. Then over the course of the peak I slowly start to pull myself together, and then post-peak it drops off and changes to the plateau stage where I feel the opposite of what I had been feeling in many ways - I feel calm, coherent, inspired, euphoric and like everything is working at maximum capacity in my brain and body, it's one of my favorite states brought on my any drug. This actually happens at the 3mg level too but when you go further with the trip the end reward is even better, or at least that was true the few times I took 4mg (one of those was 4.2mg, every little bit with DOC makes a difference because it's so potent).
Oh and the more you take the longer it will last (to a point). So 4mg will last longer than 3mg, and 3mg will last longer than 2mg. It lasts a long time regardless but a powerful DOC trip lasts even longer.
I actually find DOC to come up pretty quickly for its duration. I always get pretty strong alerts all of a sudden right at about an hour (whether I've eaten food recently or not), and then by 2 hours I'm well in it, by hours 3-4 it's at the peak. So I guess it does take a while to peak but it gets strong well before that in my experience.
