How long it will take depends on whether the application has entered the actual trial stage.
General invention patent applications need to go through preliminary examination, publication and request for real trial before they can enter the real trial stage.
The publication time of an application for a patent for invention is 18 months from the date of filing (you can request to publish in advance, but even if you publish in advance, you have to wait until you pass the preliminary examination). After publication, the applicant may request substantive examination (which must be submitted within 3 years).