You really are going to miss out on learning and many things by jumping ahead. Depending on account post quality the good signature campaigns might not even want you. A lot of these farmed accounts are utter crap on post content.
Also you will be dealing with possible shady people/shady side by doing this so possible scams.
I know I should, I plan on still using my newb account too, but for the sole purpose of having an extra income, and the fact that I don't know how long these sig campaigns are going to last. I would hate to level up all the way to Sr. In like 6 months or so with great content and all the sig campaigns are gone.