How Does A Changed Nofollow to Dofollow Link Affect SEO?

I have been having this thought pondering on my mind so I decided to ask the community. The question is: A link that was already rel=nofollow and then crawled by Google, and later changes to dofollow or have the rel=nofollow removed, how does this affect Google’s ranking?:

  1. Does it possess the same power as having the dofollow originally?
  2. Does Google sees this as trying to manipulate and not favor it?
  3. Does it possess power but not up to when it is given originally?