Our attorney made an error and it delayed my wife's spousal visa for 3 months. As stated above, an attorney cannot expedite the process, and YOU still have to do all the leg work. After the attorney's mistake, wife and I took charge and completed the interview process, Removal of Conditions, and wife's N-400 citizenship processes ourselves....with no issues or errors.
18-24 months is average time from I-130 submission to spousal visa in hand. Why? Because there are thousands and thousands of people already in the pipeline ahead of you.....and EVERY form must be scrutinized and vetted by human eyes at USCIS, NVC, and the Consulate.