You say your MC "obviously" has powers. Is this obvious because he/she is part of a superpowered team where everyone else has powers so the MC obviously does as well, or is it simply obvious because of course your main character is going to have superpowers to put him/her on par with others that do?
The more obvious it is to the reader that superpowers exist in your world and that your MC could conceivably have one, the longer you can have your MC go without revealing the MC's superpower or even that he/she has a superpower. Your readers will probably expect and certainly go along with the idea of you MC having a hidden power.
On the other hand, if in your world the only people with superpowers are green-skinned, four-armed aliens and your MC is not a green-skinned, four-armed alien, then you'd better make it clear early on that your MC has some secret powers up his sleeve. Otherwise the reveal that he does risks feeling like you're breaking your own rules.
You don't necessarily need to explain precisely what the power is until the proper moment, but you'd definitely better lay the groundwork for your character having a power, and hints at what sort of power it might conceivably be, especially if the powers risk conflicting with reader expectations.
Let's look at a couple examples. First, the X-men universe.
Superpowers are a clear part of the setting here. If you were telling an X-men story, you could conceivably go right up to the end of the book before having your MC suddenly discover a superpower and use it to save the day. You'd still most likely want to include foreshadowing and other clues that your MC isn't entirely normal, as well as hints at what his/her power might ultimately be, but your readers would accept this without blinking. There's no real limit on when you can reveal the existence of the power and no real limit on the type of power your MC can have, because in the X-men universe anyone can have basically any power whatsoever.
Finding an example where the MC goes a long way through without discovering his/her powers is rather more difficult (I suspect that most people who want to write books about superpowers want to actually showcase the superpowers early and often), so I'm going to use The Way of Kings by Brandon Sanderson, because the MC goes probably about three-quarters of the way through the book before discovering that he -- or anyone -- has magical superpowers.
The important thing in The Way of Kings, though, is that the readers are informed in the prologue that magic exists and how it works. So when the MC notices a few...odd things happening around him, it's very clear to the reader that the MC is unconsciously using magic. To the characters, it seems like just coincidence: the lethal arrows that just barely missed, the somewhat faster than expected recovery from injury. Nothing explicitly magical, but it works because the reader has seen how the magic can be used to make arrows miss or to recover from serious wounds.
The important thing, overall, is to not leave the reader without hints or expectations for too long, regardless of what you do to the MC or the other characters. In some settings (like the X-men), this requires no particular work on the author's part. If it's established that anyone can have superpowers, then your MC having some will be no big surprise even if the superpowers themselves are exceedingly rare. Readers expect main characters to be rare or unique.
If, on the other hand, having superpowers requires certain conditions to be met or superpowers only come in variety X, then you the author might have to do a bit more legwork if your MC doesn't clearly meet those conditions or if his powers are to be of type Y. Readers also expect authors to follow the rules they've established and not pull random abilities out of their hats at the last moment.