Unfortunately, there isn’t a firm answer to this question. The amount of time you have to wait from the time you submit a naturalization application to become a U.S. citizen until the time you receive your interview varies dramatically.
The biggest factor in determining your wait time is which USCIS field office is handling your case, which is assigned to you based on your zip code. For example, the service center in El Paso, Texas is taking about 13 months to process the N-400 while the Los Angles service center is taking around 16 months. Currently, the average is about 14 months.
If you have more questions about naturalization, be sure to check out this guide.