in theory, if your competitor only has 1 backlink you should outrank him/her with 2 backlinks.... all things being equal that is. But in SEO all things are never equal, so I doubt that even 2 links will be enough to outrank your competitor. Even all 3 links might not be enough, but it depends on a lot of things, honestly.
For example, what spot are you ranking on right now, without these backlinks? Because if you're ranking on page 1 for the main keyword and your site is not fresh then 1 backlink could be enough if it's a good backlink. But if you're ranking on page 4 for example, then even those 3 links might not be enough, but even if they are, there are still other factors to be considered, like how good the on-page SEO of your content is, how trustworthy / topically relevant your site is (in some tough niches like finance, travel, loans, web hosting, lawyers, SEO, diets, etc) you won't rank without a strong domain.... also, the technical SEO could come into play, it's really not all about backlinks all the time, so you need to give us a bit more info about the niche you're in, the position you're ranking in, the age of your site, the quality of your content vs your competitor's content, the strength and trustworthiness of your domain vs your competitor's domain, etc.... it also depends on the quality of the backlinks themselves, so lots of things to consider...
But all this mumbo-jumbo aside, I recommend that - regardless of circumstances - you point at least 1 backlink to the content you're trying to rank, and wait 1-2 weeks AFTER the backlink has been indexed to see if the rankings improve. If they do, then that's enough and you can point the other 2 backlinks to something else (the homepage + other inner page would be my choice).
If the rankings don't improve after the link is being indexed just point all 3 backlinks to the same page.... If your backlinks are time sensitive and need to be used right now then do as the other guy said: point 2 backlinks to the inner page and 1 to the homepage
