Honestly, there are some HUGE cons to an FM at this age. The biggest is that he can not report what he is hearing. If the FM is not working properly, he will be left with compromised sound (ie static all day) and he won't be able to tell you that is what he hears.
Since he is at home all day, with minimal background, that is a big risk to take for such little added benefit. You would likely be making speech very minimally louder, and not at all clearer. Most oral advocates do not recommend an FM before school age.
