I would pull twice a day. I can always feel a 'buildup' that occurs by late afternoon (it comes out in my jaw, I notice I clench it when I am feeling really toxic). By the time I get home I head straight for the bottle (of oil!) I don't remember feeling it quite that intensely before I used to pull, but maybe I felt that crappy ALL the time so did not notice it so much. It is not as intense as it used to be the first few months, but I definitely notice a difference in how I feel if I skip my second pull.
I have also noticed that after awhile the pulling gets ALL your eliminatory functions going - so you may still be dumping toxins well after your morning pull and it is building up in your system since it is not being eliminated properly in other ways, yet.
Expect the first few weeks to off and on experience these types of detox reactions...normal. I even go through spells every few weeks where my body is 'working' on something and I will have a few days of really dumping a lot of stuff. If you are a weenie like me and hate feeling bad then go for the gusto and pull again (until you feel better) or drink detox tea or slap on some detox footpads at night to help eliminate some of the excess gunk. Pulling is pretty effective, and I definitely feel better doing it twice daily than just once. It also gets your metabolism revved before dinner - another added benefit!