You can build backlinks even if your site is 1 sec old, without any problems. But not in thousands, go slowly in the very beginning. Google will take weeks/months to see all those backlinks.
About scrapebox blasts, I have blasted for many sites so far(both my own and of others), and none of them had any bit of trouble so far.
But of course you don't want to blast on millions of pages for a 1 day old site.
The best places to know more about these safety measures are hardcore black hat SEO forums where they have much more experience and they actually deal with black hat techniques. WJ is not the best place to learn SEO.