You can probably change before your academic fourth year (end of second or third). If you’ve already taken all the credits to be promoted to fourth year it might not make a lot of sense to change your degree in fourth year and have to worry about taking more courses and hitting credit limits (I would study the academic calendar and maybe talk to an advisor). Of course this depends on what major you’re going to be in, especially if it doesn’t have a lot of requirements. If it has a lot of requirements it might be a better idea to aim for a combined major between your favoured specialization and your current one, or to do a minor instead.