Nevada Revised Statutes (NRS) 10.155 provides that "unless otherwise required by a specific statute, the legal residence of a person in Nevada is that place where he has been physically present within the state during the period for which residency is claimed. Legal residence starts on the day that such actual physical presence begins."
So it looks to us like the minute you make Nevada your legal residence (by actually physically domiciling yourself here, which could mean anything from sleeping on the floor of your sister's dorm room to relocating to a 10,000-square-foot mansion in Lake Las Vegas), you’re a resident.
NRS 10.155 further states that "if a person leaves the jurisdiction of his residence with the intention, in good faith, of returning without delay and continuing his residence, the time of absence is not considered in determining the fact of residence."
In other words, you can't start to establish residency in Nevada if you intend to return to your former residence.
However, if there’s some dispute over whether or not you live in Nevada, NRS 41.191 states that “a declaration of domicile may be made by filing a sworn statement with the district court in the county where the person is located, evidencing residence and intent to make that location a permanent, predominant, or principal home.”
So you can go to court, show some evidence of your Nevada address, and declare your intent to become a resident. (How often this happens, we don't know; if you have evidence of residence, you can just get an ID or driver's license at the DMV.)
Of course, all this is predicated on the fact that you actually physically reside here. If you don’t and are just trying to avoid/evade state taxes elsewhere, you takes your chances.