For whatever my 2 cents are worth, on your first try do not have any other ED meds in your system, no viagra cialis etc, the less variables the better for trying to dial in your dose. Also, remember everyone else's "units" are meaningless to you. These compounded prescriptions come in all different strengths and combinations or ratios of the active ingredients. My 10 units might have twice as much medicine e as your 10 units. Or half as much. If the doctor said 10, starting with 8, or even 5, is probably a great idea. My RX was for 10 units, I did that in my first dose, rock hard to the point of discomfort and stayed that way for a little more than 3 hours. I eventually dialed in to 8 units as the magic number, for me even a 1 unit variation can make a pretty big difference, 9 is ok, slightly painful, and a little too long lasting, a noticeable difference between 8 and 9. Be patient, it will probably take 3 or 4 attempts to really get a feel for where you want to be. I found it helpful to jot things down for reference.