Monster Hunter: World has a robust character creation system, so don't be afraid to tool around with it. In fact, be extra-certain everything's in place before you hit "Start," because the opportunity to change your Hunter later is a bit limited.
While you can change some aspects of your character by visiting your room (once you have access to it via the Tradeyard), other aspects, like gender, are locked in stone. Some players would love to have the option to perform a complete make-over on their characters. It might happen in the future—if there's enough fan demand.
Monster Hunter: World Producer Ryozo Tsujimoto spoke to Game Watch Impress about the game's character creator at the Taipei Game Show 2018 yesterday (via SiliconEra). "You can't redo it, but when making a character you can check their expressions, so you might want to do that first while making a character," he says. "However, if there's enough demand for it then I'll put [a character redo option] under consideration."
Monster Hunter: World's Director, Yuya Tokuda, says players should make sure to take advantage of the daylight and nighttime lighting previews on the character creation screen. "You can change the lighting on the bottom-left. Using that, not only see what it's like during the daytime, but you can also check the expressions and such for night. I think if you use that while making it, it might not be as off."
Speaking for myself, I spent about 10 minutes throwing together my main avatar, then 30 minutes agonizing over my Palico.