EMS mobile command/advice going forward

Hi, I am sort of new to the game, I have been playing for about a month and I was just wondering at what point should I invest in training people for EMS mobile command? Here are my current statistics! My main 2 dispatch centers have 29(fire stations, 13 or so ambulance/ems) but I also have rural departments that surround these with about 7 extra stations, currently, I am in a small but realistic alliance where we each cover cities/counties and currently I am in about 4 or 5. This is in southeastern Virginia for context, now let me get back to my point. When should I train people for ems mobile command? I have also heard you can put them in BC cars, is this true? and finally, how should I scale my operation? Do you suggest I go for more Fire stations or go more ems? (Also I have 4 stations, sorry I am really tired and trying to include everything). I also cover 2 airports and I am starting to expand into more military stuff for ARFF operations and the VDOF(Forestry/brush). Sorry for rambling but any help would be appreciated!!

Thank you for the advice, I think I am going to start training now and then add on more EMS. I am currently working on putting a volunteer EMS department in my setup. Currently I only have 3 stations but I am working on it as I have a private ems in my main area. All of these are within an hour from top to bottom and I have 2 cities where I have a fair amount of coverage. Do you think I should go for more fire stations or instead venture out more into the EMS world or get a few more Fire stations first? (Also not I am probably going to do separate EMS on top of FD when I will fully finish my setup as I hear that is the best way to go).