Just a quick question: can you start out with an omniscient pov and then switch to the character's pov after giving some exposition?
What do you mean by 'the charchter's pov'? Do you mean switching into first person? If so, going from Omnicient to first person is a very jarring shift - like cruising in 3rd gear and suddenly jamming it down into 1st. Don't grind the transmission unless it's REALLY important.
There's 3rd-limited Pov, which is still written in third person, but keeps the focus on one character - what that character can sense - and that character's thoughts.
A transition from omnicient to 3rd limited is more natural, but still potentiall confusing.
My rule of thumb is that the more fancy maneuvers you make, the more narratorial skill is required. In other words, a very strong, clear narrator - who gives the reader sense of "I know what I'm doing, trust me" will be able to navigate the reader through any and all changes in POV without throwing them out of the story.
And as they will wisely ask you time and again out here "is this necessary?" Are you just doing some fancy stunt driving for the sake of showing off? Are you competent to drive such a vehicle in such a way?
Think of the reader. Understand the reader's POV over everything else, and realize that your job is to engage them - not the other way around.