It all depends on the company. I know people who had interviews, and in some cases, job offers, 9 months before graduation. Other companies didn't even start posting full-time positions for a May-July start until March and April with interviews in April and May.
If you are at a university, I would recommend talking to your university's career counseling office. I know such a service is pretty common in the US, and they have people who work with students in preparing resumes, determining when to apply, and interact with companies who are hiring particular majors. They would know which companies are posting positions for post-graduation hiring.
Regardless of where you are, if there are any companies that you are particularly interested in, you can check out their website and even reach out to their HR departments or submit resumes to a generic resume drop if they have one and don't have any positions for the time you are interested in. Get your name out there and see if anyone is interested.