I see no reason why you can’t begin pumping as soon as you like, it’s not going to hurt you as long as you know what you are doing. I’d suggest you head over to the pumper’s forum to get the basics down, if you’re thinking about it.
Ultimately, you can use an ADS as well if you want, I doubt it’ll do any harm. Again, as long as you know what you’re doing. Because ADS is actually a very light tension stretch (less than manual stretching), you don’t need to ‘toughen up those penile tissues’ prior to its use. In some regards it’s actually safer than manual stretching since the tension is far less, spread over a longer time. That being said, there is still a lot to know about correct use, wrapping, etc.
Pumping itself also doesn’t require pre-conditioning. It is even prescribed in some cases as a viable treatment for ED, which obviously don’t require conditioning.
I have always percieved the pre-conditioning recommendation of the newbie routine primarily aimed at preparing your penis for exercises like clamping and hanging, as well as various other advanced techniques. But these two in particular are the ones that really call for conditioning, as they are potentially quite dangerous.