I was wondering how do people time their interviews?

For non college students (because college students generally get through career fairs or apply at specific timings during their semester so looking to hear more from current working people who shift after couple of years of working):

• Do you all start studying first and once have made yourself familiar with all concepts, do you start applying to companies? or the other way round?
• Do you reach out to recruiters and then start figuring out the plan to focus on specific companies? I am wondering if someone reaches out back and then they want to schedule the interviews next week and you arent yet prepared.
• How many companies do people generally target at once?