I would like to ask the following questions. What are the responsibilities of a junior developer? Will he/she be given a task to develop a new project from the start without any supervision? What if he/she gets stuck and can't find any solution? If that was happening to me, I would be in panic mode! Also how about training?
Varies a lot by company but generally at the start you will get very simple tasks with offer of support from your direct senior dev. However this will usually ramp up fairly quickly and by 2 months in you'll be expected to be working fairly independently and not having to ask for help much. You'll just be kept away from very sensitive and complex areas of code most likely. Having a start/finish project after an initial month or 2 isn't hard to imagine.
It's up to the company, and it can vary. But typically, a junior developer is given tasks suitable to a less experienced developer. It MIGHT be a start-to-finish project, but more than likely I'd guess it would be as a team member, under the supervision of a senior developer/team leader. Most companies allow said developer to get familiar with the company and codebase before expecting much.