Well, I’ve been PE’ing for 3.5 months. In retrospect, I consider the first two months to have been a ‘warm-up’, i.e., preparation for ‘serious’ exercise. During that time, all stretching and jelqing (which was all I attempted at the time) seemed stressful and left me a little sore. I was gradually able to spend more time and apply more force, and have now added light weights and pumping, and am just getting into clamping. My rule of thumb was to increase effort to ‘almost’ the point of pain — a tricky threshold to find and maintain. And I also started applying more heat throughout the workout, by doing all my initial strectches in the shower, and returning to the shower every 15-20 min. during the workout (which is now an hour or more). A typical stretch now requires both hands to achieve that threshold.
In other words, don’t rush it. I didn’t notice any significant gains until three months and wasn’t really expecting much. Play it safe and focus on conditioing rather than gains. I believe you need to improve the pliability, esp. of the tunica, and improve blood flow, before you can do a really strenuous workout. Stretching and jelquing mainly, but also try ‘bundling’ (search for that term), which involves twisting while pulling. Lots of variations on stretching are available. Add reverse jelqs and squeezes judiciously. Remember that you’re a newbie for atleast three months :-) Above, all, learn to read the signs (search for “physiological indicators”).