An infection could take a lot longer than days. They can take weeks, months, or in some cases years to develop. You may never know it's there. If you follow proper cleaning and sanitation, it likely will not be an issue. The reason people say that it's a risk is because more things to clean and sanitize means more things potentially not clean and sanitized enough. Like most things in life, the more variables involved, the more likely something is to fail.
The bigger issue is going to be oxidation, especially if you just funnelled from jars into a carboy, which will introduce a veritable asston of unwanted oxygen into your fermented beer. With talk of using k-meta for infection and ascorbic acid for oxidation, it sounds like you're reading about brewing (or perhaps it's more winemaking where those are used a lot more), but taking too much too fast and not seeing where things fit. That "a little knowledge is a dangerous thing" kind of scenario. With proper care and proper procedure, you would never need to use either of those things in a finished beer, and if you were taking your time and not rushing to know everything right away, you'd have known as much. (I use k-meta all the time for treatment of my brewing water, but that's for removal of chloramine and has zilch to do with preventing infection). I don't know if ascorbic acid would help you here or not. My guess is that it would require so much that you'd be bound to have major off-flavors from it.
Now, it does take a lot more oxygen than you'd think to actually stale a batch and cause the liquid cardboard sort of oxidative flavor, so there's no guarantees. But once fermentation is done, essentially no oxygen is best and the more oxygen that reaches your beer the worse. Unless you've got a super fancy set up I couldn't even dream of, avoiding all contact with oxygen will be impossible, but you don't want to do anything that deliberately adds it (like, say, dumping fermented beer from a jar through a funnel into a carboy).
But as mentioned already, read Palmer's "How To Brew" before you think of starting another batch. I think you'll find things go much smoother if you wait to "be experimental" until you've got your fundamentals under control (which you don't at this point). Keep things simple at first, go by the book (pun intended) and your beer will thank you for it.