I'm not sure I understand exactly. I guess you are not telling a time-travel story; so this sounds like a long flash-back. If it is a romance, I think you destroy much of the suspense in a romance by pre-telling how things turn out.
Typically a book opens with "the normal world" of the protagonists. Things are happening, but not important things, we are just establishing who they are (character), what the setting is, how they respond to everyday problems.
Then something important to the plot happens: Typically in a romance, the people meet. (When Harry Met Sally actually compressed this very effectively; essentially the lovers meet nearly in the opening scene, and then are "trapped" in a car for many hours traveling to NYC.)
Suspense in a novel is important. Readers turn the pages to find out "what happens next", how things turn out, in the next few pages, in the next chapter, by the end of the book. Much of writing is finding the conflicts you can create so you can overlap these threads of suspense, resolving one conflict but creating another. (You do have to resolve them; the reader can't be left hanging on all of them forever; that is why you need short term, medium term, and long term conflicts.)
In a romance, these conflicts are basically disagreements and incompatibilities and logistics (In Sleepless in Seattle, a NYC woman falls in love with a guy on the radio, that lives in Seattle). Basically, all clashes of personality or situation or identity, due to language, nationality, religion, location, and often class, wealth, fame, or power (e.g. Pretty Woman, Notting Hill, You've Got Mail).
When Harry Met Sally notwithstanding, romances also tend to have a fairly rapid timeline; the book brackets a few years from meeting to commitment.
This is the worry I have with your jump-ahead-a-year strategy; you will reveal too many facts of the story, and kill the suspense of "will they or won't they" -- We know they end up together, so their conflicts feel empty. (You could say we know that they end up together because it IS a romance; but that is an intellectual exercise, and the story is an emotional one, so it isn't the same as seeing them together.)
Nor does it do much good to replace the romantic suspense with suspense about some event in the year-from-now story.
Technically, I'd tell a student doing this they are writing a long flashback, and they shouldn't do it. Flashbacks are largely out of fashion, precisely because they kill the suspense of immediacy, the feeling the reader has of things happening now as they read them. Instead, they feel like they are reading history. They know, from your opening, the problems you are presenting have already been solved.
So they trudge through this history lesson to get back to the "now", which is wherever you left them, a year after the stuff they are reading. It might be interesting, but just like a taped sports event when you already know the final score, it isn't as interesting as when you don't know the final score. Even though, intellectually while watching a tape, you do know the outcome is inevitable -- but emotionally it feels like it is happening now. The same is true for any book or movie, you know the ending is fixed and written a year or more ago; but it doesn't feel like that emotionally.
I don't know your plot, but if it is a romance, have some patience and tell the romance linearly, preserve the romantic suspense. Then whatever you wanted to open with a year later comes as a surprise and good action and more suspense.
The advice to start "in media res" does NOT mean you have to start with some big bang. It means start in the middle of some action, with one of your main characters actually doing something, but this can be anything: Waking up late for work after sleeping through a power failure. Waking up with a hangover in a strange bed. Missing the bus for school. It doesn't have to be plot-point actions.
"In media res" is actually basically a "Don't open with EXPOSITION" advice, don't open telling the reader about the world, and its history, and describing the physical attributes of your character, and TELLING us a bunch of stuff.
You open with action because that lets you introduce a minor conflict and that generates your first little bit of instant short-term interest, in one sentence you can have the reader wondering "what happens next." That is nearly impossible to do with exposition and explanation and building a setting with descriptions. Sentence 1:
Karla woke up gradually, without an alarm, then in sudden alarm she looked at the blinking clock: Power failure ... Holy crap I'm late for work!
In 25 words you have conflict, you have character, and that will pull the reader through a 1000 words to find out what happens next. In that 1000 words, you can build more setting (as Karla interacts with her environment), more Karla character (as she sprints through her morning routine), and set up another short term conflict and perhaps a medium term (chapter closing) conflict.
As I said, I'm not sure why you want to start in the future, but I suspect you are trying to jump into the big-story-conflict too quickly, and that doesn't work. Readers won't care about your big conflict if they don't feel like they know your characters. Conflicts between strangers aren't very interesting because there aren't any stakes we care about, we don't know who the good guy or bad guy is, we don't know if Karla is lying or telling the truth about about Jenny, etc. Even if Karla is sick, we aren't sure she doesn't deserve it! Don't be afraid to write about them up front, reader's will give you the credit to develop your world and characters for the first 1/8th of the story. As long as you keep it interesting (a series of short-term conflicts woven together), readers don't need anything BIG to happen, they are happy to get their bearings with your characters and in your world and they will trust you to trap their new friends in a house fire, eventually.