From the minute you inject your first shot, your hormone levels are raising. You may not feel it like you will in several wks, but it is working. Your body will get more and more anabolic as each day passes. Yes, it will take a few wks for your gear to reach supra physiological levels, to the point that you look bigger and see changes in your strength, but you can rest assured that from day 1, your gear is working. So you see where I'm going with this. There really isn't a NEED to cover that first 4 wks with another substance. If your diet is on point and your training and rest are good, you will start to make gains. Even your HCG is going to increase test levels quickly, from the first wk you use it. 

That being said, I understand that you want to get the most out of your time being "on". I wouldn't suggest an oral, as 12 wks of orals is kind of a long time. So maybe something like TNE, taken at 50mg ED for the first 3 wks. On training days, I would take it 1-2 hours before you lift. If it is too much of a commitment to inject IM ED, you can do what I do and use a 1cc insulin pin, 1/2in 29g, and inject it sub q. I have no problem putting 1/2cc in my love handle