It all depends how fast you want her in the US. If money is no object but speed of reunification is the main objective, then file for a fiancée visa (6 months). Otherwise the whole thing could take up to a year and a half.
Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
Come back from Nepal. File I-130, cooperate with the US government at all levels they might ask for, wait about three years and meet the spouse at the airport in one of the Americana cities of your choice.
The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter,not should it be viewed as establishing an attorney client relationship of any kind.
You can go with either Attorney Behar's advice and file a fiancé petition for which she will come to the US and you two will get married if as he stated money is not an issue but speed is the main objective, or with attorney Segal's advice and file an I-130 after you marry her if it is the other way around.
Gunda J. Brost Brost Law Office This advice does not form an attorney-client relationship and is merely informative. It should not by itself be relied upon to address a legal concern.
You could file after getting married (no fiancee visa for permanent residents). Processing guess is about 6-7 months at current but could changeanytime.
My answers are for general information only, NOT A legal advice because these are not tailored to your specific situation. Contact an Immigration Attorney if you need legal advice.